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i 3 1176 00166 4490

DOE/NASAI0189-81/1NASA CR-165291

NASA-CR-16529119810022489

Testing of the PermanentMagnet Material Mn-AI-C forPotential Use in PropulsionMotors for Electric Vehicles

Zouheir Abdelnour, Herbert Mildrum,and Karl StrnatUniversity of Dayton

March 1981 SEP 1 7 1981

LiBf,/lIiY, fjASA

111"~!Jrj;tl"l\.l~ Mn~\~\!.l.

Prepared forNATIONAL AERONAUTICS AND SPACE ADMINISTRATIONLewis Research CenterUnder Contract DEN 3-189

forU.S. DEPARTMENT OF ENERGYConservation and Renewable' EnergyOffice of Transportation Programs

https://ntrs.nasa.gov/search.jsp?R=19810022489 2018-07-10T04:47:42+00:00Z

NOTICE

This report was prepared to document work sponsored by the United StatesGovernment. Neither the United States nor its agent, the United States Department ofEnergy, nor any Federal employees, nor any of their contractors, subcontractors or theiremployees, makes any warranty, express or implied, or assumes any legal liability orresponsibility for the accuracy, completeness, or usefulness of any information,apparatus, product or process disclosed, or represents that its use would not infringeprivately owned rights

DOE/NASA/0189-81/1NASA CR-165291

Testing of the PermanentMagnet Material Mn·AI·C forPotential Use in PropulsionMotors for Electric Vehicles

Zouheir Abdelnour, Herbert Mildrum,and Karl StrnatUniversity of DaytonElectrical Engineering DepartmentDayton, Ohio 45469

March 1981

Prepared forNational Aeronautics and Space AdministrationLewis Research CenterCleveland, Ohio 44135Under Contract DEN 3-189

forU.S. DEPARTMENT OF ENERGYOffice of Transportation ProgramsWashington, D.C. 20545Under Interagency Agreement DE-AI01-77CS51 044

CONTENTS

PAGE

SUMMARY II .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 1

INTRODUCTION .•....... . • . . . . . . . . . . . • . . . . . . . . . . . . . • . . • . • . .. 2

BACKGROUND INFORMATION ON Mn-AI-C MAGNETS 2

MA TERIAL AVAILABLE FROM MATSUSHITA ELECTRICINDUST. COMP. . ................................•........... 4

TYPICAL PROPERTIES ADVERTISED BY MATSUSHITA 5

DATA REQUIREMENTS FOR TRACTION-MOTOR USE OFMn-AI-C AND THE GENERAL PLAN FOR OUREXPERIMENTAL STUDIES. . . • . . . • . . . • . . • . • • • . . . • . . . • . . . . • • . .. 6

MAGNET SAMPLES USED IN OUR TESTS AND SUMMARYOF MEASUREMENTS MADE ON THEM ......•...........•....•• 9

MECHANICAL TESTS 16

SUMMARY OF MAGNETIC RESULTS .....•............•.......• 18

CONCLUSION AND SUMMARY OF RESULTS .....•..........•.•• 26

APPENDIX I: HYSTERESIS LOOPS, DEMAG. CURVES,MINOR LOOP FIELDS-FIGURES 7 THROUGH 42 ... 28

APPENDIX II: LIST OF SYMBOLS•••...........•.............. 65

REFERENCES 66

iii

TESTING OF THE PERMANENT MAGNET MATERIAL Mn-Al-C FOR

POTENTIAL USE IN PROPULSION MOTORS FOR ELECTRIC VEHICLES

SUMMARY: The development of Mn-AI-C permanent magnets is briefly re­viewed. The general properties of the material are discussed and put intoper spective relative to alnicos and ferrites. The commercial material nowavailable from the Matsushita Electric Industrial Co. is described by the man­ufacturer's data.

The traction-motor designer I s demands of a permanent magnet for potentialuse in electric vehicle drives are reviewed. From this, a list of the neededspecific information is extracted. A plan for experimental work is made whichwould generate this information, or verify data supplied by the producer. Theseplanned tests and measurements were executed in our laboratory.

The results of these measurements are presented in the form of tables andgraphs. The data is discussed and interpreted. The tests determined magneticdesign data and some mechanical strength properties. Easy-axis hysteresis anddemagnetization curves, recoil loops and other minor -loop fields were measuredover a temperature range from _50°C to +150°C. Hysteresis loops were alsomeasured for three orthongonal directions (the one easy and 2 hard axes of mag­netization). Extruded rods of three different diameters were tested. The non­uniformity of properties over the cross section of the 31 mm diameter rod wasstudied. Mechanical compressive and bending strength at room temperature wasdetermined on individual samples from the 31 mm rod.

This report presents the data as measured in considerable detail. In this formit would be of use in motor design calculations. Simpler summary graphs andtables that allow one to get a quick picture of the behavior of Mn-A l-C magnetsin general are also included. If the use of this material in motors is seriouslyconsidered, more information about the temperature dependence of the flux atdifferent operating points, irreversible losses on heating, and the long-term fluxstability at elevated temperatures should be generated.

1

INTRODUCTION: Experimental characterization of the magnetic and somemechanical properties of the new permanent magnet material, Mn-Al-C, wascalled for in support of work undertaken by various groups designing propulsionmotors for electric vehicles. The characterization work has now been completedand the results are herewith reported. However, to put our data into the properper spective and make them more meaningful, the report sections on our exper i­mental results are preceded by a general background discussion of Mn-Al-C, areview of the properties reported for it in the literature, information on theavailability of the material, and some economic considerations.

BACKGROUND INFORMATION ON Mn-Al-C MAGNETS

In the last few years the Matsushita Electric Industrial Co. in Japan hasdeveloped to commercial maturity a permanent magnet material which isbased on a manganese-aluminum intermetallic phase. 1,2 Basically thesame material had first caused excitement as a potential new permanentmagnet about twenty years ago. Several industrial magnet laboratories(including those of the Indiana General Corporation in the U. S. 3 and thePhilips Company in Holland 4) attempted then to develop useful propertiesand fabrication methods, but the results were disappointing. No commercialproduction resulted, and work in the U. S. was discontinued. The principalproblem was that of obtaining a sufficiently good metallurgical grainorientation which would result in a single-easy-axis magnetic anisotropyand, as a consequence, should yield good remanence, squareness of theintrinsic magnetization curve in the second quadrant, and a high energyproduct.

Development work continued, however, in Japan. As the result of a deter­mined effort in the last decade, scientists at Matsushita developed a techniqueof warm extrusion and heat treatments which res ults in a favorable crystaltexture 5 and in technologically interesting magnetic properties. Chemically,the material was slightly modified by the addition of small amounts of carbonand nickeL (The C metallurgically stabilizes the hardmagnetic phase, andthe Ni facilitates extrusion. )

In terms of their room teInperature magnetic properties, the best Inagnetsof this kind (as described in Matsushita publications) combine moderatelyhigh reInanence values (B r RIll 6 kG), approaching those of Alnico 8 HC, witha coercive force (Hc~ 2.7 kOe) in the rang e of that of high-energy hard

2

ferrites. This H c is four times that of Alnico 5, or 1. 5 times that ofAlnico 8. The energy product of the best Mn- Al- C (7 - 7. 5 MGOe) iscomparable to that of grain- oriented Alnico 5. The material is notbrittle like Alnico or ferrite; it has a moderate degree of ductility and ismachineable on a lathe or milling machine with carbide~tipped tools. Theseare unusual mechanical properties for good permanent magnet materials,whichmus t normally be shaped by grinding or electric discharge machining,or by other special techniques suitable for hard and brittle materials.

However, all these advantages (there are also some drawbacks; see below)might not have sufficed to give the material a promising commerCial future incompetition with the well-established Alnico magnets, had it not been for acobalt supply crisis which developed in 1977-78. Cobalt is the principalalloying partner of iron in the higher-grade Alnicos (24-38% Co). Cobalt isa by- product of either copper or nickel production, and the United Stateshas relied heavily on the African countries, Zaire and Zambia, as itscobalt suppliers. For a variety of reasons, the price of cobalt quintupledbetween mid-77 and mid-79, from about $5.00 to $25.00 per pound, andthere was a time when manufacturers found it difficult to purchase cobalteven at this highest price. In contrast, manganese and aluminum - theprincipal constituents of the magnet material discussed here - are at present·quite inexpensive (about $0. 60/lb.), and the raw materials are plentiful.(It should be noted, however, that the U. S. presently imports practically allits manganese. )

In any case, due to the cobalt shortage, magnet users and producers havelooked for potential replacements for Alnico, and the ,Mn-Al- C magnetsare one attractive possibility. 6

On the negative side, it must be said that the Mn-Al-C has a very low Curietemperature, -290°C, compared with 700°C to 800°C for the Alnicos and450 ° C for the ferrites. This has the consequence that all magnetic designpara·meters of these magnets are strongly temperature dependent, and the valuesof B r , H c ' (BH) max' etc., fall off rapidly as the magnet is heated aboveroom temperature. Another apparent drawback at the present time is thatthe warm extrusion is a difficult process requiring heavymachires andtherefore large capital inves tmentj short lifetime of the extrusion diesappears to be a problem too. This has the consequence that the presentprice of Mn-Al-C magnets is in the same range as that of orientedAlnico 5. It is quite possible that, in spite of the low raw materialprice, Mn-Al-C may remain a relatively expensive magnet material inthe long run.

3

MATERIAL AVAILABLE FROM MATSUSHITA ELECTRIC INDUST. COMPo 7

The need for the extrusion step puts restrictions on the shapes and sizesin which the material can be manufactured. The material is alwaysextruded in the form of a long rod of relatively small and simple eros s­section, with the easy direction of magnetization along the extrusion axis.(But note that Matsushita has also published a laboratory method ofproducing a lower-energy magnet featuring an isot§opic easy plane ofmagnetization perpendicular to the extrusion axis. This is achieved bycutting aslice from the extruded bar and subjecting it to additional plasticdeformation steps. Such a material could have application in small size,multi-pole structures such as the rotor in certain stepper motors.) In itslaboratory pilot production, Matsushita has apparently produced a varietyof rods of circular cross section, ranging from about 4 mm to 31 mmdiameter. Some of these sizes are now going into a larger-scale commercialproduction (including 4 mm, 6. 5mm and 3lmm rods). Engineering samplesof sufficient quantity for the evaluation in motors were promised to theGeneral Electric R$ D Center and possibly other U. S. customers for deliveryin October 1980. Bars of rectangular cross section 5 x 10 mm were saidto have been extruded successfully, but the problems of die wear and breakageare apparently so severe that no commercial production is contemplated atpresent.

According to information given '.IS by Mr. Sakamoto during his visit at theUniversity of Dayton in May 1980, and earlier conversations with him andMr. Kubo during K. Strnat's visit to the Matsushita Research Center atOsaka in June, 1979, Mn-Al magnets have been in a pilot line production therefor 3 -1 /2 years now. Several million pieces of"'" 1 gram weight, cut from 4 mmand 6. 5mm extruded bars, have been sold to electric clock manufacturers.(This is a total quantity of several tons.) Slices from 24 and 3lmm diameterbars were used in commercial loudspeakers by another division of theMatsushita Company. A "pancake", axial-field electric motor for abicycle drive is apparently also in commercial production. It uses the31 mm diameter discs.

A new commercial manufacturing plant has recently been built by Matsushitaabout 100 miles from Osaka. It was scheduled to begin production in thesummer of 1980. The production plan includes 10 diameters of circularrods, from 4 to 31 rom.

Matsushita continues to be the only source for Mn-Al- C magnets in theworld. Apparently, no other company has been licensed by Matsushitafor their patented extrusion process; and although the laboratories-of Brown,Boveri (Switzerland), Colt Industries, General Electric, General Motors

and the Indiana General Corporation say that they are doing some Rand Dwork, there is no prospect for a commercial production outs ide Matsushitain the near future.

4

TYPICAL PROPERTIES ADVERTISED BY MATSUSHITA

Table 1 and Figure 1 are reproduced from an illustrated Panasonic announce­ment and data sheet received in May 1979. The sheet was undated, but theproperties agree well with thos e given in Ref. 2 (July 1977), from whichTable 2 is taken. Note that Table 2 contains some additional informationnot in Table 1.

TABLE 1:

Specifications (Preliminary)FIGURE 1: Demagnetization Curve of Anisotropic Mn·AI·C

Permanent Magnet

Item Symbol Unit Mn·AI·C Magnet(anisotropic)

Maximum Energy Product (BH)max x10' G·Oe 5.0 - 6.0

Residual Induction I Br G 5.200 - 6.000I

Coercive Force ! He Oe 2.000 - 2,600

Permeance Coefficient at (BH)max i Bd/Hd GIOe 23

Average Recoil Permeability I Pr GIOe 1.0-1.2

Reversible Temperature Coefficient at Br I 'Iorc -0.12

ICurie Temperature I Tc I 'c 300

Density d glcm' 5

!Resistivity I ,n x10·'f!·cm 80

;Coefficient of Thermal Expansion x10"/oC 18

i Hardness (Rockwell C) I HRc - 50- 55

ITensile Strength kg/mm' >30

iCompressive Strength , kg/mm 2 >200

!Transverse Strength kg/mm' >20

TABLE 2: Summary of properties (Ref. 2)

Energy ProductBdlll-1d (MG·Oe)

I6

6000

5000

4000gj"~..

£?Q)

3000

2000

'000

°3000 2000 1000 °Demagnetization Force -H (Oersted)

116m Symbol Unit ~.AJ-C magnet(anisotropic)

-Residual Induction (BrI G 5200-6000

~rciv(l Force (He) Oe 2000-2600Maximum Energy Preduct (SH)rnax x 10 6G'Oe 5.0-6.0

1----(Bd) G 3600Band H at ISH),...

(Hd) Oe 1550Permeance Coefficient

(Bd/Hd) GIOe 2.3~~·nml'Avera$e Recoil Permeability lJ,LrI GIOe 1.0-1.2Recoil Energy Product (Ed x 106G'Oe 2.2R.lversible Temperature %/'C -0.12Coefficient at Br

Curil3 Temperature ITcl ·C 300Jl.lx.olute W.axim...-n Tcmperatexe °C 500f--.

(dl glcm 2 5.1Density

Resistivity (p) x 10.6 0 'em 80Coefficient of Thermal x 1O-6/,C 1aExpansion

~pecific Heat Cal/gOC 0.15Hardness (Rockwell C) (HRc) - 50-55~sile Strength kg/mm 2 >30Compressive Strength kg/mm2 >200Transverse Strength kg/mm 2 >20Machinablity , - machinable

FIG. 2: Demagnetization Curvesfor Anisotropic Mn-Al- C Magnetat Different Temperatures.(From Reference 1, Ohtani et al. )

r---~---"------'7

lJ/H

3 cn

2

-I

H (kOe)

5

Another 1977 news release9 gave somewhat more optimistic upper limitsfor the remanence (6200G) and energy product (7 MGOe). The demagnetizationcurves at different temperatures shown in Fig. 2 are from Ref. 1 (we drewin the B/ H load lines). They belong to a magnet that has 7 MGOe at +20 0 C.

Mr. Yoichi Sakamoto provided us with machining instructions for turningMn-AI- C magnets on a lathe. Thes e are reproduced here as Table 3.Mr. Y. S. stated that on ordinary SiC cutoff wheel may be used, too, andwe have also succes sfuHy cut the material with an electric dischargemachine (EDM).

DATA REQUIREMENTS FOR TRACTION-MOTOR USE OF Mn-AI-CAND THE GENERAL PLAN FOR OUR EXPERIMENTAL STUDIES

1. For the contemplated use of Mn-AI-Cmagnets in the rotors of tractionmotors, it would be desirable to have a high air- gap flux density of about6 kG. However, if the magnet is placed directly at the gap, as in the GEaxial-field, " a dvancedmotor" design, 10 B ga is only about 3 to 4 kG ifthe material is used close to its maximum vofumetric efficiency. Thehigh motor currents possible during vehicle climb or in a stall/ start condition,and the self-demagnetizing fields due to the air gaps, require that the magnethave a high resistance to demagnetization. The coercive force of Mn-AI-C,....,2600 Oe at room temperature, is relatively favorable compared to thevalues for Alnico grades (600-1900 Oe).

Nevertheles s, the combination of B r and Hc offered by Mn-Al- C is saidto require the use of large magnet blocks in the motors. These are cubesor trapezoidal prisms of about 1 inch edge length. Considering the productionlimitations on Mn-A1-C shapes and sizes, each such block must be assembledfrom several pieces that have to be cut from the 31 mm cylindrical extrudedstock. In the process, certain inner portions of the bar are selected for use,while some of the outer rim will be cut off and discarded. It is thus desirableto know if there is a variation of properties over the cros s section. Oneaspect of our experimental study addressed thi!3 question.

.f. The flux direction in the magnet is not always or in every volume elementparallel to the easy axis of magnetizationll (i. e., the extrusion axis in Mn-AI- C).Attempts to take this fact quantitatively into account in the design of machinesrequire a detailed knowledge of the magnetization characteristics of thepermanent magnet, not only for the easy-axis magnetization direction forwhich they are usually published by the manufacturer, but for three mutuallyperpendicular directions. 12 We undertook it to describe the magnetic aniso­tropy by measuring major hysteresis loops forthe extrusion axis, the radialand the circumferential (lltransvers e") directions of the 31mm extruded bar.This was done at several temperatures, and at room temperature f?r twolocations on the bar cross section.

6

TA BLE 3: MACHINING CONDITIONS FOR THE ANISOTROPIC l{n-Al-ePERHANEHT HAmlET us ING A L..~TF~

Bit ----------...----------- Cement:ated Carbide B:L-l;Rotating Speed ----------- 1,1l5 r.p.m.Feed ----------------------0.02-0.03 mm/revQDepth of Cut ------------- 2.0 mm(rough), 0.25 mm(finish)Nose Radius of Bit ------- 0.1-0.2 mmShape of bit

·Surface Cetting ----- Point Nose straigh~ ~ool

end relief angle (4-6°).Edge Cutting ------- Knife Tool

"'<"d/'" I side cutting edge angle (5-10°)

~::, I

end cutting edge angle (20°)

nO=j1 ;~ang1e (5-10°) aral1e1 rak(5~~i

reliei angle (4_6°)"--------side relief angle (4-6°)

• Drilling ---------- straight Drill (all cenentedcarbide drill)

Received June 26, 1980from Mr. Sakamoto of:

Matsushita Electric Industrial Co., Ltd.CENTRAL HESEARCH LABORATORIESMORIGUCHI, OSAKA 570, JAPANTEL OSAK/\(OG)909-1121 CABLE "MATSUDEN MOFiIGUCHI" TELEX MATUSITA J 63426

7

1.. According to the motor designers we interviewed on this question,the new vehicle traction motors are designed to operate at winding tempera­tures of about 150°C. Peak temperatures of 180°C to 200°C might betolerable from the point of view of electrical insulation and structuralintegrity. Although the magnets will generally be cooler, they certainly

I

could get as hot as about ISO°C unless special provisions are made forcooling them. Because of its low Curie temperature, Mn-Al-C showsfairly severe flux losses on heating. While the generally reported tempera­ture coefficient of Br(H=O) is moderate (- 0.12% per °c, average betweeno and 100°C) inspection of the set of curves in Fig. 2 shows that theintrinsic coercive force and hysteres is loop shape deteriorate much morerapidly on heating than does the zero-field remanence. As a consequence,the temperature coefficient of the useful flux density, Bd at a realisticoperating point of perhaps Bd/H

d= -2.3 to -2.5, is going to be much less

favorable. Also, the losses above 100°C will rise at an increasing rate.The severe loss of MHc on heating means a poor resistance to demagnet­ization under the combined influence of motor overheating and large currentsduring a prolonged steep climb, an operating condition that must be expectedon occasion. The designer, who must protect the magnet against demagnet­ization under such worst-case conditions, thus needs detailed information aboutthe temperature dependence of the hysteres is curves and recoil loops. Whilelow temperatures do not pose a threat to the stability of Mn-AI-C magnets,their characteristics down to the lowest expected environmental temperaturesshould also be known. With these reguirements in mind, we measureddemagnetization curves B vs. Hand (B- I{)vs. H over the range from - 50°C to+1S0°C.

4. The variable effective air gap during motor operation, current surgesoccuring for any reason, or partial disassembly of the motor cause themagnet material to change its operating permeance, to "recoil, " and thusto work on a minor hysteresis loop in the second quadrant of (B-H) vs. H.We have measured recoil loop fields (full recoil to H=O) at several differenttemperatures in order to allow designer s to accurately as ses s the effectsof such operating point changes.

For some samples (at room temperature only) an extended minor-loopfield was plotted with the recoil lines continuing through the first quadrantto the full original forward magnetizing field. Thes e curves will be usefulin determining how to initially charge the magnets in the fully or partiallyas sembled motor, or how to remagnetize them after accidental demagneti­zation, or in similar operations. Minor loop fields were plotted only forthe extrusion axis, i. e., the normal magnetization direction.

8

MAGNET SAMPLES USED IN OUR TESTS ANDSUMMARY OF MEASUREMENTS MADE ON THEM

The following is a description of the samples as received and as theywere prepared for the measurements by us. We also present tablesof the commonly given room-temperature quantities as reported by theMatsushita Research Laboratory and measured by us. This sectionwill also serve as a guide to the following recorder plots and graphswhich show the detailed results of our measurements.

Sample Group I

• Material supplied: Three cylinders, 6.4 mm diameter x 8mm long,magnetized along axis. Cut from 6.5 mm extruded rod stock byMatsushita. Received at Osaka on June 3, 1979. These samples weremachined and selected by Matsushita. Room temperature hysteresisloops were measured and provided with the samples. The cylinders weremarked as No.6, 7 and 8.

• Reported composition: 70 wt. % Mn, 29.5% AI, 0.5% C. (Letter from Mats. )

• TABLE 4. Salient Room-Temperature Magnetic Properties:

Data By: Matsushita (26 0 C) Univ. of Dayton

B r MHc (BH) B MHcIdentification

m r

Mat. U. Dayton kG kOe MGOe kG kOe

No.6 M-1483 5.95 2.63 6.0 6. 17 2.72

No.7 M-1481 5. 96 2.61 - - 6. 17 2.74

No. 8 M-1482 5.98 2.75 - - 6. 18 2.82- --

MGOe

6.4

6. 5

6. 5

.Comments on these results:

Note that Matsushita reported conservative numbers. We measuredslightly higher values for remanence, coercivity and energy product.This is unusual. We nonually find the claims of vendors exaggeratedand measure lower properties than reported by the producers.

9

• Measurements made on these samples:

1. Major hysteresis loops at room temperature(RT = 25°C), for all three cylinders. Intrinsicloop, (B-H) vs. H, directly recorded. Normaldemagnetization curve, B vs. H, manually drawn.(Figures 7, 8 and 9 - See Appendix I)

tdl) 5

-, /T-"I '

I f

H

2. Recoil loop fields, 2nd quadrant (abbrev. Q-2)curves (B- H) vs. H (directly recorded) andBvs. H (manually replotted from B-H curves).For sample M-1482 (No.8) only; 25°C.(Figure 10)

B

B-H3. Minor loop field, (B-H)vs. H. From Q-2 and

Q-3 back to +H peak. For sample M-l482(No.8) only. At 25 ° C.

(Figure 11)

Sample Group II:

• Material supplied: One disc, N31mm diameter x 6 mm thick,magnetized through thicknes s II cylinder axis II extrusion direction.Cut at Matsushita from ",.31 mm extruded rod stock. (Pilot plant product,probably early 1979). Received at Osaka on June 3, 1979.

• Samples machined at U. Dayton for magnetic measurements:Two cylinders, 6.35 mm (1/4 11

) diameter x 6mm long wereEDM machined from two locations, the center of the disc andnear the rim, as shown in the sketch.

• Reported Iitypical tl composition: 69.5 wt. % Mn, 29.3% Al,0.5% C, 0.7 wt. % Ni. 31 mm

diameter

• TABLE 5. Salient Room-Temperature Magnetic Properties:

Matsushita (22 ° C) University of Dayton (25° C)

B r MHc BHc (BH) Sample B MHc BHc (BH)mm r

Identification

kG kOe kOe MGOe kG kOe kOe MGOe

5.7 2.7 2.3 5. 1 M-1638 5.48 2. 91 2.44 5. 1

Measured on the whole disc M-1639 5.85 2.93 2.52 6.0

10

• Measurements made on these samples:

1. Major hysteresis loops at RT (25°C) forboth samples, (B- H)vs. H. demag. curve

B vs. H manually drawn in. (Figures 12 & 13)

2. Recoill00p fields, Q-2, (B- H)vs. HandB vs. H " For center sample M-1638 only,

25 ° C (Figure 14)

3. Minor loop field, (B- H) vs. H, from Q- 2and Q-3 back to +H peak. For centersample M-1638 only, 25°C (Figure 15)

• Objectives of tests:

1. To study the variation of properties over the cross section of theextruded rod.

2. To study the dependence of the magnetic properties on the diameterof the extruded stock.

3. To generate minor and recoil loop fields characteristic of the largestdiameter rod stock (31mm) in pilot production before June 1979.(Compare with minor loops of the small, 6.5 mm rod stock ofSample Group 1. )

• Notes on results:

1. Again, it appears that Matsushita reported properties conservatively.Our weighted average energy product value would be almost 6 MGOe,compared with Matsushita's 5. 1 MGOe.

2. The B r and (BH)max for the 31 mm rod are poorer than those of the6. 5mm rod stock. It appears that the smaller the diameter of theextruded bar, the better is the grain orientation achieved, and thereforethe remanence, loop squareness and energy product.

3. There is a radial gradient of the properties. B r and (BH)max near therim are about 7% and 18% higher than the respective quantities at thecenter of the rod. This is certainly due to better crystal orientation.It is likely that the greater shear stres ses near the die wal,l during theextrusion process favor the formation of the desired crystal texturethere.

11

Sample Group III:

• Material supplied: Discs, 3lmm diameter x 8.15 mm thick, magnetizedthrough thicknes s II cylinder axis II extrusion direction. Cut at Matsushitafrom 31 mm extruded rod stock. (Commercial product, early 1980).Received by mail from Mr. Sakamoto in June, 1980. (Letter dated 5/29/80.)

• Samples machined from Disc B at Inland Motor IKollmorgenand the University of Dayton:

(a) Three cubes, along a diameter; one at centerof disc, two symmetrically located halfwaybetween center and rim. Edge length 8. 13 mm(0.320 inch). Axes parallel to extrusion direction,a radius, and a tangent to the circumference(lltransverse direction ll for outer cubes)

(b) Two bars of cross section 3. 18 x 3. 18 mm (0.125 inch)and ""27 mm length, located as shown in sketch.

• TABLE 6. Salient Room-Temperature Magnetic Properti.es:

M-1646

Matsushita (27°C) Univers ity of Dayton (25 °C)

B r H BHc (BH) Sample B MHc BHc (BH)M c m r m

Identifica tionkG kOe kOe MGOe kG kOe kOe MGOe

5.45 3. 15 2.55 5.0 M-1646 5.84 2.85 2.43 5.4

Measured on the whole disc. M-1647 5.86 2. 87 2.42 5.3(Identified as sample B)

• Note concerning the magnetic meas uringmethod:

The UD values in the above table are from hysteresis loops measured witha (B-H}-compensated coil arrangement. It uses a close-fitting, centered,surface H-coil that inductively senses dH/dt for both the H deflection andthe H-flux compens ation. For the meas urements of the temperature anddirection dependence of properties, another coil fixture was used whichcontains a square H-coil identical to the B-coil, and where these coilsare side-by-side rather than cpncentric. The absolute accuracy of theconcentric coils is better than for the side- by- side (lldual COUll) arrangement.However, only the latter allows controlled temperature variation. Theuse of these different coil arrangements is the main reason for the minor

-12-

variations between magnetization curves measured on the same sample atthe same temperature. The curves are presented as-measured, and noattempt was made to normalize all values to the concentric- coil values asa standard. For most purpos es, the difference s are negligible .

• Measur ementsmade on the cubic samples. (All the meas urementsdescribed below were performed on all three cubes but only the hysteresisloops of cube M-1646 are shown in the Appendix. )

.B-H .B~1. Major hysteresis loops at RT (25 ee):

(B- H) vs. H measured and B vs. H calculated.Note that equivalent measurements weremade with the concentric coils and with thedual coil. The latter was first used by itselfwith the sample in direct contact with the yokepoles, and then inside a heating/ coolingfixture which contains fixed extension polepieces that may introduce minor air gaps.(Figures 16, 17, and 18)

2. Q-2 recoil and full minor-loop fields at RT asbefore, for easy axis only, us ing the dual co ilswith heating / cooling fixture in place.(Figures 19 and 20)

3. Major hysteres is loops for all three cubeaxes at RT, using the concentric and the dualcoils with fixture. (Anisotropy measurement. )(Figures 21 and 22)

4. Easy- axis major loops (B- H) and B vs. H at thetemperatures -50°C, ooe, (t25°e, see No.1)t500e, tlOOoe and t150oe. Dual coils withfixture. (Figures 23 through 27)

H

5. Major hysteresis loops for all three cube axesat -50°C, ooe, (t25°C), t500e, tlOOoe and+150 °e. Dual coils with fixture.(Figures 28 through 32)

6. Q-2 recoil loop fields (B-H and B) for the sametemperatures. Dual coils with fixture. Easyaxis. (Figures 33 through 37)

7. Q-2 demagnetization curves (B-H and B) forall temperatures, summary graphs (recordedindependently). Dual coil with fixture. Easyaxis. (Figure 38)

13

-1-4 ......+-+-+-~-H --+44-4-+--'

uiahT~

Sample Group IV:

• Material supplied: Two cylinders, 6.35 mmdiameter x 30 mm long. Magnetized in longdirection II cylinder axis II extrusion direction.Machined at Matsushita from 24 mm extrudedrod stock. (Presumably pilot line product,early 1980). Sample location on bar crosssection as shown in sketch.Received from Mr. Sakamoto in June, 1980.(Letter dated 6/10/1980.)

• Samples cut at U. of Dayton for magnetic measurements: Four cylinders ofdifferent lengths from each of the two bars. (D:6. 35 mm : 1/4 inch).

TABLE 7. Dimensions and Open-Circuit Permeances of Cylinders.

Length mm 8.8 7. 1 5. 6 4.2LID - - 1. 40 1. 12 0.89 0.66

Bd/Hd G/Oe 5 4 3 2

Relationship betv.r~en LI D and Bd/Hd based on the ballistic demagnetizationfactor of Joseph.

• Reported llTypical" Composition (per Matsushita letter):69.5 wt. % Mn., 29.3 wt. %AI., 0.5 wt. % C •• 0.7 wt. % Ni.

• TABLE 8. Salient Room-Temperature Magnetic Properties.

Sample Length B r MHc BHc (BH)mIdentification mm

kG kOe kOe MGOe

Matsushita (27°C) - Average for 24 nun extruded rod.

Extruded Rod -- 5.45 3.3 2.75 5.4

Univ. of Dayton (25°C) - 2 samples cut from 6.35 mm cylinder.

M-1642 8.84 5.69 3.44 2.83 5.8M-1643 5.59 5.66 3.46 2.83 5.7---

M-1644 8.84 5.72 3.44 2.85 5.9M-1645 5.56 5.64 3.42 2.79 5.6

Average Values -- 5.68 3.44 2.83 5.75

14

• Note concerning the measuring method: The hys teresis loop measure­nlents on these samples (as on the 1/4 11 cylinders of Sample Groups I and II)were made with a (B-H)-compensated coil arrangenlent with a closelyfitting, concentric surface H- coil us ed for the H-deflection and the H-fluxcompensation. The pole faces of the magnetizing yoke (Varian 4" DClaboratory electromagnet) were in close contact with the sample ends.(B-H) was calibrated against pure iron standards of dinlensions close tothe samples. The saturation of Fe was taken as 21,580 Gauss.

• Measurements made on these sanlples:At room temperature only, full hysteresis loops (B-H) vs. H wererecorded, and 0-2 denlagnetization curves B v s. H were calculatedand manually drawn into the recorder graphs. This was done fortwo of the four samples of different length which were cut from eachof the two 1/4" rods received. (See Figures 39 to 42 and the abovetable. )

• Objectives of the tests:

1. To characterize material from the third extruded rod diameteravailable to us, i.e., 24mm rod stock. (Compare with 6.5 mmand 31 mm measured before. )

2. To document the initial room-temperature properties of these sampleson which we plan to nlake open- circuit flux stability studies at alater date.

3. To compare again our measurements with those of Matsushita.

4. To demonstrate the slight variation of our measured values forB r and (BH)max on the length of the sample for presumablyidentical material.

• Notes on the results:

1. Again, we measure slightly better properties (all! See table) thanMatsushita reported: +4% for B r and MHc' +3% for BHc' and+6.5% for (BH)max'

2. There is a slight dependence of the properties - nleasured with ourcoil arrangenlent - on the length of the sanlple. It is in the sensethat the measured values of B r , BHc and (BH)max are slightlylower for the shorter samples than tor longer ones. Comparing the8. 8 mnl and the 5.6 mm cylinders, the differences were .... 1% forB r , "'1. 2% for H, and "'3. 5% for (BH) ,notmuchmore thanthe reproducibifltyClinlits. H is inde~;cfent of the sanlplegeonletry within the error Il~~d~, as it should be.

15

3. The remanence and energy values for this 24 mm rod stock lie betweentho se of the 6. 5mm rod and those of the 31 mm rod, but closer to thelatter. Using the Matsushita figures (because they are averages overthe whole rod eros s section), the salient proper ties are compared in Table 9.

TABLE 9. Comparison of the Salient Magnetic Properties.

Rod Diameter B r MHc (BH)m

mm kG kOe MGOe

6. 5 5.95 2.63 6.0

24 5.45 3.30 5.4

31 5.45 3. 15 5.0

• Plans for future experiments on these samples:We hope to conduct temperature cycling and elevated temperature/long-term flux stability studies on the samples of Group IV. Inthese, the open- circuit remanent flux would be measured at differenttemperatures, and as a function of time-at-temperature, with aresolution of O. 01%. The different L/D ratios determine differentBd/Hd operating permeance and allow one to simulate the circuitbehavior of the magnet at different operating points.

MECHANICAL TESTS

.!.. Machining Experience

During the machining of test samples it became obvious that the extrudedMn-Al-C (Ni) alloy is not really ductile at room temperature. While it cancertainly be machined with carbide tools according to Matsushita's instruction,the workpiece chipped severely during drilling on the exit side. In spark­erosion machining (EDM), too, a piece broke off the corner of one cube. Thelatter fracture may have started at a flaw that was present in the 31 mm discfrom the extrusion process. The fracture surfaces look like those ofceramics and are indicative of brittle fracture.

2. Bending Test for Flexural Strength

According to the test plan, room-temperature bending tests were performedon two specimens cut from a 3lmm disc. (Sample Group III; see sketch onpage 12 for sample location, specimens 4 and 5.) However, only the ultimatestrength was determined. The samples were too small to instrument themfor elastic modulus and Poisson's ratio measurements, as was originallyintended.

16

The flexural tests were performed on prismatic bar specimens of3 x 3 x Ao-26 mm (0.13 x 0.13 x .... 1 in) size, with the load appliedparallel and perpendicular to the magnetization II extrusion direction.The long direction of the bar was essentially along a diameter of the31 mm disc, i. e., a magnetically hard axis. The samples were magnetized.

Four- point flexure testing was used in preference to a uniaxial tensiontest for several reasons. Uniform- stress, uniaxial tensile tests usingthe familiar "dogbone" shaped specimens would be too wasteful of material.We did not have enough to make standard- size samples. Moreover, directtension tests are very susceptible to parasitic stresses resulting fromeccentric loading, and to cracking of specimens in the test grips, in thecase of brittle materials.

In contrast, the four-point flexure test uses a very simple specimengeometry and permits the use of quite small samples. Under load, aconstant moment is developed between the two inner load points.Consequently, a uniform surface stress is developed over a significantportion of the sample and valid test data can be obtained for failureswhich occur anywhere in that region. To minimize errors from fixturemisalignment, friction effects, and contact point wedging, a kinematicallydesigned bend fixture is employed. This fixture incorporates the basicdesign features recommended by the NATO Advisory Group for AerospaceRes earch and Development. A universal tes tingmachine is us ed to loadspecimens at a rate intended to produce failure in not les s than two minutes.

From the machining experience described above we had reasons to suspectthat the material is indeed relatively brittle. The fracture mode of theflexure test bars confirmed this. The broken surfaces again look likethose of the machining fractures, and there is no evidence of plasticdeformation before failure of the bars.

TABLE 10. Results of the Flexure Tests:

Specimen Dimensions Load Ultimate Strength

Type b[mm] d[rnm] [kgf] [MPa] [kgf/mm2 ] [kpsi]

FUM 3.23 3.24 27.3 150.8 14.8 21. 9

F..LM 3.34 3.21 31.6 171. 0 16.8 24.8

17

3. Compressive Strength Test:

Cube M-1647, cut from the 31 mm diameter stock, Sample Group III, wassubjected to a compressive strength test. An Instron Universal Tester withself-alignment fixture and load pacer was used in this compressive strengthtest. A suitable test fixture had been fabricated during a previous programand was available for this inve stigation. The sample was loaded in the com­pression fixture with the force parellel to the extrusion direction II magneticeasy axis II.thickness of the cylindrical disk A-3. A stress-strain curve wasrecorded. Numerical values for Young's modulus of elasticity and for ultimatestrength were derived from the curve (Figure 3, Top and Table 11). T-typestrain gauges were bonded on the side of the cube thus measuring strain in boththe longitudinal and transverse directions for given static loads. A transversestrain vs. longitudinal strain curve was plotted (Figure 3, Bottom) from whichPoisson's Ratio was calculated (Table 11).

TABLE 11: Numerical Res ults of the Compres sive Strength Tes t for Cube M-1647

DIMENSIONS: b = 8. 11 mm = O. 3193 In.

d = 8. 01 mm = O. 3153 in.

COMPRESSION FAILURE LOAD = 8550 kgf = 18,800 Ibs.

2ULTIMATE COMPRESSIVE STRENGTH = 1290 MPa::: 131 kgf/mm = 186.7 kpsi

YOUNG'S MODULUS, E = 180,000 MPa = 18,300 kgf/mm2

= 26,000 kpsi.

POISSON'S RATIO, " = 0.25

SUMMARY OF MAGNETIC RESULTS:

The results of all the magnetic measurements performed on cubes M-1646,M-1647 and M-1648 are summarized in Tables 12, 13 and 14. In the graphicalrepresentation of these results (illustrated by Figures 4, 5 and 6), fLr, therecoil permeability, was arbitrarily defined as the slope of the line connectingthe two tips of the minor loop for complete recoil from the operating pointB/H = -2.5 GIOe.

18

FIGURE 3: Top: Partial Stres s - Strain DiagraITl for DeterITlination of

Young's Modulus for Cube M-1647.

BottoITl: Longit. Strain - Transv. Strain DiagraITl for DeterITlinationof Poisson's Ratio for CubeM-1647.

TABLE 12. SUMMARY OF THE AVERAGE MAGNETIC PROPERTIES OF CUBE M-1646

No

Measurements at 25°C Measurements at- low and high temperatures.with 3 different coils. Dual coil with heating/ cooling fixture.

CONC.DUAL DUAL

COILSCOIL COIL -50°C O°C +25°C +50°C +100°C +150°CW 10 Heat With HeatFixture Fixture

0r:<l

5.77 6. 12 5.89 5.77 5.64 5.25 4.78p::; B [kG] 5.84 5.79::J rU)

~<t; ---r:<l f-l U)

~~

0 ~ H [kOe 2.85 2.88 2.85 3.36 3.04 2.85 2.59 2.06 1 .46U) f-l <t; M cPi ~0 ....:l U)

0 r:<l <t;....:l ....:l r:<lU)

....:l" H [kOe] 2.43 2.45 2.39 2.74 2. 53 2.39 2.22 1. 82 1 .31...... <t; - B c

U) p::;U)r:<l P: ......

p:j ~r:<l

0<t;

f-l Z HK

[kOelU) ....:l 1. 35 1. 32 1. 30 1. 48 1. 38 1. 30 1. 22 1. 00 0.70~ r:<l 0.....::G ......

U)~ ::J

~ ::G ~ (BH)0 f-l f-l 5.4 5.3 5.2 6. 1 5.5 5.2 4.9 3. 8 2.7P:: .....

~max

~ ~ r:<l [MGOe]

Z3.06 2.94 3. 15 3.06 2.94 2.92 2.67 2.34o " R --

....... jrI-- B [kG]U)U)

::J ..... r 3.00 -- 2.91 3. 15 3.06 2.91 2.86 2.67 2.31p::;~ Tf-l<t;~ R 3.49 -- 3.43 4.00 3.69 3.43 3.24 2.64 1 .98r:<l MHc [kOe-i -::G T 3.45 -- 3.43 4.00 3.67 3.43 3.24 2.61 1 .98

':' R = Radial Direction; T = Tangential Direction.

60

6=0- B-f;' r

5 5

4 4

3 3

2 2

x HKx -x )(....

1 -x- l-)(

0 0- 50 0 25 50 T[OC] 100 150

f.1r, (BH)m

BHc [kOe] [MGOe]

Temperature I:'ependence of Selected Second QuadrC1nt Propertiesfor Cube M- 1646.

5

3

o

4

1

2

6

150100o

H ._+__ B c .

+---~+

_____<>y.---'Il<) f.1r <> <>-----~

6

5

4

3+

2

1 0

0-50

FIGURE 4.

21

TABLE 13. SUMMARY OF THE AVERAGE MAGNETIC PROPERTIES OF CUBE M-1647

NN

Measurements at 25°CMeasurements at low and high temperatures.

with 3 different coils.Dual coil with heating / cooling fixture.

CONC.DUAL DUAL

COILSCOIL COIL -50°C 0° C +25°C +50°C +100°C +150 ° CW /0 Heat With HeatFixture Fixture

Qr:L1

5.86 5.78 5.76 6.08 5.91 5.76 5.64P:i B [kG] 5.30 4.78:::> r(f) r:L1<t:; iI: -r:L1 f-l (f)

;:;s.....

0 ><: H [kOe 2.87 2.86(f) f-l <t:; M c 2.85 3.34 3.07 2. 85 2.61 2.08 1 .47P-t :>-<0 ....:I U)

0 r:L1 <t:;...:l ....:I r:L1(f)

....:I II H [kOe] 2.42 2.39 2.40 2.73 2.54 2.40 2.23 1. 81 1 .31..... <t:; B c(f) P:i (f)r:L1 <t:; .....!Xi P-t ><:r:L1

Q<t:;

f-l Z H [kOel(f) ...:l 1. 32 1. 27 1. 28 1. 45 1. 35 1. 28 1. 20 0.98 o .69:>-< r:L1 a K.....iI: .....

(f)~ :::>;:;s iI: ~ (BH)0 f-l f-l

5.2 6.0 5.6~ ..... ><:max 5.3 5. 1 5. 1 4.8 3.9 2 .7

~ ~ r:L1 [MGOe]

Z 3.04 - - 2.99 3.23 3.06 2.99 2.91 2.72 2.38o " R........... ii"'

I-- [kG]U)(f) B:::> ..... r 3.02 2.93 3. 15 3.06 2.93 2.91 2.64 2 .35P:i><: T --f-l<t:;><:

R 3.45 3.44 4.04 3.62 3.44 3.27 2.65 1 .97r:L1 MHc [kOe--

-i I--

iI: T 3.44 -- 3.41 3.92 3.62 3.41 3.27 2.59 1 .97

':' R = Radial Direction; T = Tangential Direction.

B r [kG],

HK [kOe]

6 6

5 5

4 4

3 MHc 3

2

~2

• H Kx- x x-l -x- l

-)C

a a-50 a 25 50 T[oe] 100 150

f-l r •(BH)

BHc [kOe] [MGO:JJ

Temperature Dependence of Selected Second Quadrant Properties

for Cu~ M-1647.

6

5

4

3

2

a

1

15010050 T[oe]25a

H_'+--. B c+---+--------+------<> f-lr <> () ...:t>

6

5

4

3 ...-2

<>1

a-50

FIGURE 5.

23

SUMMARY OF THE AVERAGE MAGNETIC PROPERTIES OF CUBE M-1648TABLE 14.Meas urements at 25· C Measurements at low and high temperatures.with 3 different coils. Dual coil with heating/ cooling fixture.

CONC.DUAL DUALCOIL COIL

COILSW 10 Heat

-50°C O°C t25°C t50·C t100°C +150°CWith HeatFixture Fixture

Clrilp::; B [kG] 5.84 5.76 5.76 6. as 5.87 5.76 5.62 5.30 4.78::J rU)

~<!; -ril E-tU)

;:;E.......

a x MHc [kOe 2.88 2.84 2.84 3.32 3.05 2.84 2.59 2.08 1 .47U) E-t <!;Pi >-<0 ....:I U)

0 ril <!;....:I ....:I rilU)

....:I" BHc [kOe] 2.44 2.44 2.40 2.72 2.54 2.40 2.23 1. 84 1 .31....... <!; ~

U) p::;U)ril <!; .......

!Xl Pi Xril

Cl<!;

E-t Z HK

[kOel 1. 35 1. 29 1. 28 1. 45 1. 38 1. 28 1. 23 1. 03 0.70U) ....:I>-< ril 0~

....... .......~

U)

~::J

~ ~ (BH)a E-t E-t5.6~ ....... X

max 5.3 5. 1 5.2 5. 9 5.2 4.9 4.0 2 .7~ ~ ril [MGOe]

Z 3.02 - - 2.92 3. 15 3.06 2.92 2.87 2.64 2.32a RH ~~

~ B [kG]U)U)::J ....... r

3.02 2.92 3. 14 3.06 2.92 2.85 2. 63 2.32P:;X T --E-t<!;X R 3.49 3.44 4.02 3.67 3.44 3.21 2. 62 1. 97ril MHc [kOe

---i -:r: T 3.45 -- 3.44 3.99 3.67 3.44 3.20 2. 59 1 .97

>:< R =Radial Direc Hen; T =Tangential Direction.

B r [kG],

H K [kOe]

6 B r 6

5 5

4 4

3 3

2HK

2

x -x-l -x 1

0 0

-50 0 25 50 T[OC] 100 150

fJ. r • (BH)mBHc [kOe] [MGOe]

TeITlperature Dependence of Selected Second Quadrant Propertiesfor Cube M-1648.

-+---­+-----OfJ.r <> :~

5

4

3

6

1

o

2

150100

6

5

4

3 +.

2

01

0- 50

FIGURE 6.

25

CONCLUSION AND SUMMARY OF RESULTS: An experimental characterizationof selected magnetic and some mechanical properties of the new permanent mag­net material, Mn-Al-C, was undertaken in support of work by various groupsdesigning propulsion motors for electric vehi.cles. The samples were providedby the only commercial producer, the Japanese Matsushita Electric Industr ialCo., Ltd. Pieces of extruded rods of three different diameters (6. S mm, 24 mmand 31 mm) were tested.

The magnetic results may be highlighted as follows:

(1) Matsushita reported conservative numbers for the magnetic properties. Wemeasured slightly higher values for remanence, coercivity and energyproduct. This is unusual. We normally find the claims of vendors exag­gerated and measure lower properties than reported by the producers.

(2) The B r and (BH)max for the 31 mm rod are poorer than those of the 24 mmor 6. S mm rod stock. It appear s that the smaller the diameter of theextruded bar, the better is the grain orientation acheived, and thereforethe remanence, loop squareness and energy product are better. Theremanence and energy values for the 24 mm rod stock lie between those ofthe 6. S mm rod and those of the 3lmm rod, but closer to the latter.

(3) There is a radial gradient of the properties, at least in the 31 mm rod. B rand (BH)max near the rim are about 7% and 18% higher than the respectivequantities at the center of the rod. This seems again to be due to bettercrystal orientation. It is likely that the greater shear stresses near thedie wall during the extrusion process favor the formation of the desiredcrystal texture there. Not enough of the 24 mm material was available tomake a similar homogeneity check.

(4) The hardest axes of magnetization perpendicular to the extrusion direction ­in the radial and transverse directions - are practically identical in theirmagnetic properties.

(S) As a consequence of the low Curie temperature of Mn-Al-C (Tc =27S - 3000 C),all of the magnetic properties are strongly temperature dependent. Theydeteriorate very rapidly as the samples are heated to'" lSOoC. AlthoughB r only drops from N S. 78 kG at 2 SoC to.-Y 4.78 kG at lSOoC, the quantitiesMHc and (BH)max fall off much faster: the intrinsic coercive force goesfrom 2. 8S kOe down to 1. 46 kOe, and the energy product from S.2 MGOeto only 2. 7 MGOe when the temperature rises from 2 SoC to lSOoC.

(6) Detailed information was obtained on the recoil behavior of Mn-Al-C atvarious temperatures between - sao and +1 SOOC. The second-quadrantrecoil loop fields reported should be a valuable aid in the proper design ofmotors. It was found that the intrinsic recoil loops of Mn-Al-C have anunusual sickle shape. This finding is strictly of basic-science interest.

26

The mechanical tests showed the following results:

(1) The extruded Mn-AI-C (Ni) alloy is not really ductile at room temperature.While it can be machined with carbide tools according to Matsushita'sinstructions, the workpiece easily chips and one has to be very carefuLIn spark erosion machining (EDM), too, a piece broke off. The latterfracture may have started at a flaw that was present in the 31mm discfrom the extrusion process. The fracture surfaces look like those ofceramics and are indicative of brittle fracture.

From the machining experience des cribed above we concluded that thematerial is indeed relatively brittle. The fracture mode of flexure testbars confirmed this. The broken surfaces again look like those of themachining fractures, and there is no evidence of plas tic deformation beforefailure of the bars.

(2) The ultimate strength measure during the flexure tests was 150.8 MPawhen the force was parallel to the direction of magnetization, and 171. 0MPa when perpendicular.

(3) In a compression test of a cubic sample, the ultimate compres sivestrength was 1290 MPa. Young's modulus is 180,000 MPa and Poisson'sratio is 0.25.

In conclusion, it must be said that the Mn-Al- C does not look veryattractive for us e in automotive propulsion motors becaus e of the severelos s of coercivity on heating above 100 0 C. At least, the engineers willhave to carefully design for the worst-case current load at the highestmagnet temperature expected in us e. The limited sizes and shapes inwhich the material is presently available are also a disadvantage.However, there is no question that Mn-Al-C has the potential of replacingAlnico 5 in many other applications where the magnet stays es sentiallyat room temperature and/or the operating point is essentially fixed.

27

APPENDIX I

HYSTERESIS LOOPS; DEMAG. CURVES, MINOR LOOP FIELDS

FIGURES 7 THROUGH 42

PAGES 29 THROUGH 64

SAMPLE IDENTIFICATION Figures Pages

Sample Group I Cylinders from 6.5 mm rod 7-11 29 to 33

Sample Group II Cylinders from 31 mm rod 12-15 34 to 37

Sample Group III Cube from 31 mm rod(a) Room temperature data 16-22 38 to 44(b) Data for - 50 0 C to +1500 C 23-38 45 to 60

Sample Group IV Cylinders from 24 mm rod 39-42 61 to 64

28

FIGURE 7 Major Hysteres is Loops For Cylinder M-1481 at 250

C.

\JJo

oFIGURE 8 Major Hysteresis Loops E'or Cylinder M-1482 at 25 C.

I-~·

........ ; ...

·1> ....··t";I·::....!,,.i.. '

··+hL,.~·

. ,.'. ,.', ",. ...

I·

oFIGURE 9 Major Hysteresis Loops For Cylinder M-1483 at 25 C.

z

Name,20U h,,{ A8I1fLNOUJ!:.....le. J.il.!J.LKoUNtVEIlS'lTY OF DAYT_N. ),(A,CNETICS LAaOIlATOIlY

FIGURE 10 Q-2 Recoil Loops, (B-H) & B, For Cylinder M-1482 at 2SoC.

FIGURE 11 Full Minor-Loop Field For Cylinder M-1482 at 250

C.

,

-.

.,....

I.

i

+.. ".+.. ,.. ' .. , :..·i····

..

i I·

I·

.. .

._.'-'

,...... : i ;, ... .. .'

_.. . .•.•• I. ••

.--

,_ •... i ..

.. \ ...

·t ,..

....

1__ •.. _

.[ r :...

I··..._.

I : ....i

I .. ···· ,...

I·

r

:- ..

, .. ,.I·

I

,._ ......

... ! I. ... .... ,' .. I···

i I, .. L.

I.I·,..

I·· .-..

W~ ;... ... : ... i._

.... ....

,. , .. ;...

FIGURE 12 Major Hysteresis Loops For Cylinder M-1639 at 2SoC.

:

.

,,, '.:

.. .... I··

. -- ...

i .

.1

..

. + ..

.., ... L ..•

1 i

.. I... ' ...'

.1 .

. " ..

·1 ..·1·:.

L .. '.

...

..·1·

I..

i.

if

~ ..

1/ 1-'I

.. I·

! ...

,.. ,. I·· ~. c·,V, ..: " !••

I

,--

i..

I··I

I

i·..

...

I'

I·,....

.. ...

I',

I

-I·

. I·

! .+.: ..

I

•

1-·' .. " .. , .. I··,.

" .

1.; ..+--+.+ .. 1,'. i." ",.

I·

. ".1 .

. , ,

:

. !. '1-- ,. +,,',1 +.. i-I--I, j

I !

~ .. L..

,..·1--

1._.

I'I· ..·

I

Ii.,

!... ,.

.. , 1 • .. 1..· ' .1....[.-

: .,i I·1

I·'

!.

I

, ..

I.' •. '

'"

I..

,.. I ·;1..· I ...

I·

i····· I, i

.... Li, .• 1·.l"I'!. Ic'.'+'+"'i~''''~f'n/.I ruU/j:'+."I··jl'~..+ ..+•. "..+,.e"I-'+.'.'II·"+.• :...'+·+c,+'.I... ! ... !.••:I.f

i'.+.. ;, /

" I· ·,1 .•1•• 1.+".1·.\'.'1 •••·.•·••.. :1I.. I'··i·-I·I-[... "-1...,,,+...l=j·-I""[;/ :

," j, '. !' i·' .. '• ·i··,·!·.. I,.I .. +···' .. ·!·'A....I···F+...V·I·.. ·I'..j..·l +--1'·'1-'-·1',,+,,- .+-L..4 ...;

I·

'·.1.I· __ L. i· ..·

',1·,,1·

i·.·,·· I.-'i ...... ,I··I .. .... : I

,.' I,,·' , ...

• i···

I·· .•.

r I . I ..

FIGURE 13 Major Hysteresis Loops For Cylinder M-1638 at 25°C.

.. ' .....I·' i .• iT·I·c·!···I··+cY

FIGURE 14 Q-2 Recoil Loops, (B-H) &B, For Cylinder M-1638 at 2SoC.

aFIGURE 15 Full Minor-Loop Field For Cylinder M-1638 at 25 C.

FIGURE 16 Major Hysteresis Loops For Cube M-1646 at 2Soc (Using Cone. Coils).

FIGURE 17 Major Hysteresis Loops For Cube M-1646 at 2SoC (Using Dual Coils Without Hlc Fixture).

oFIGURE 18 Major Hysteresis Loops For Cube M-1646 at 25 C (Using Dual Coils With Hlc Fixture).

.........~ ......." ffn.AI-C._ ••" ItItTwsHrTIi.....' {q4<! .... ~'DJ'I"~.Dll9'(,DW" ,j.'.....,..=:=..JV.I:--=:::...cm' ...It, IIUIl] 1"-4,-.,+,j~C+-+

[lje :8~1~ iii C_,' .: :ii';"~!S12;: !y ::!~ I::;;' .

it::i'I!ii'l

'T

i

l,i".:2l.!:H' .... • Hc ·Z.l'kO•. ••'~G ;•.

'Sffl... •i4....wce.. "x .I:.!£...t.. T-: Z';"c f:.......u.... ia H _ ~k" :/.A.;;.DrUI!LF COIL ~

, nr:-" "TUR~ t

"-me: ZQIJ4,,/ AA})£ltVIJV~.t.:...Q..C.L-' ,.ci.::"~EIt!lTT eF a"YT.N. WAGN!;TICS L ....O..A.TO.. Y -

FIGURE 19 Q-2 Recoil Loops, (B-H) &B, For Cube M-1646 at 2SoC (Using Dual Coils With Hlc Fixture).

") I-

- ,-~

FIGURE 20 Full Minor Loop Field For Cube M-1646 at 2Su

C (Using Dual Coils With Hie Fixture).

FIGURE 21 Major Hysteresis Loops For All Three Cube Axes For M-1646o

at 25 C (Using Cone. Coils).

FIGURE 22 Major Hysteresis Loops For All Three Cube Axes For M-1646 at 2SoC (Using Dual CoilsWith HI C Fixture).

.

.

.., ..

.i

, I1 .. '1·'

.. [.0., ...,..i

i

' ..

"" ..'.,. , ,

i""I J

.

,. ,

. ...

. ~ : ' II.

," I...

,. I·,· . .. , .. 1-. ;- .. ' .... Ie--

, ,,··i..' ...

, .

!

,.. i···

.-

I.

, .. ,.. , ,...

·1..· ,

I... '.'. ..

" ..

1"'." ',' "

. ,..

I'···....

. ,'

......... ."

I., ,i

I"

"~I

I,II, ,I,

I

i, Ii

!

,. ,'"I,

•f~I'" . ,... ,.-1/ I·,

i·,.- ",. ' i"V i', ..~-

./,-'Ic, i-,·i

0-.. , .. .

'.','"' ..

,·1,·

i-,-.,

oFIGURE 23 Major Hysteresis Loops For Cube M-1646 at -50 C.

FIGURE 24 Major Hysteresis Loops For Cube M-1646 at OOC.

..

,.....-

-

..

! --

.. -_.i

I !"

; ..! I ..

--,

'.

:,.

--' .'

.-.-...

,--'.+-,-1.. '

, .1 .. " __

..

1 -

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.

!

,-_ ..i

--.','" '.-_.:~

T__ j.

--.l .

,.,- ;---

-- ".- ... ,-I..;·

.,---~_._--.,- ..---

...

.

----

; C -... -

.. I

--_. --

So.m,I.N•.~I.rl.I·~ _

"om, MAISVS»W$ ,.: Cm'tle. 0Un.~~/W I":--.:::::::JV.I:~_cm) "'halty ,,=--llcm

l

MHc' ~J... •He .2.2'-"0•. a. ,i~~c

laHlm ·tlwce.. '\< .I..ll.~ tf~:~,cc,'1 .. :...,Mr.....tl .... I. H, .....ll.-k.. !)IfH~t F.'lf"rt

Nama £ A • L l. L • )\.lR _o.t./J?LJijJoUNJVUSlTi¥,Ht' ff\O\2iON. MAG!'(dics·l. ....OItATOIIIV

---

- .:

,--

! ..

.

i ,_ .' .. ! ..

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--.----- 1--··--._, ;

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:

-

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: ;

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[kG]

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I

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---

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.--

.

-:--!

1

un.. If-·v

--

I·

+--!_+_. ..; !....i. ..

.. '", ...

... "",..

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,_ .... -.

.,.-- -, .. ..,.. -

! ' .••

.

---- ,--,---

,. '

..

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.

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....

,.-

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--

1 ..

i._.,

,-.. C

.

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:

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_.

... "'.....-

-'.- '--I--"'~"----!'+

~...,+__ +.,+1" __1__ .. '_

... _'

.:: ., .. ! -' !... 1- ..

:

FIGURE 25 Major Hysteresis Loops For Cube M-1646 at +50°C.

oFIGURE 26 Major Hysteresis Loops For Cube M-1646 at +100 C.

.," .

:

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.: . "

....

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....

...

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:

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I··· ,.'. ii I' iTI· : ..

··+·i" i·· f· H'!.:

." i· 1 jI

.. .

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,

.' :

i·· ..

i···· .• r-

... ,.:....

....... ...

i...._. I·:· .,

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'J......•..

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• ••': I'·

,.'::: "

.,,•.•.. + <: i ••, ..

. ,..... " ...,: ..

" +T ........I·

t• i ••

, ..... .....

... . .. ,

• L_. . ...

...•."!' I., t.... .: .

.. I'.....

.. ..

:

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J J 3w"",ht, -==....J Vol- -==-cm Denei.,: --"::::,,,,-.Icm

Iol"c ~&-'t2...'!~. •He ~/·30k ••. •r·~C

,".,_ ..Z~_MGOo... •O,Lr:;>.". ~';'~~Co:1..,...<1,.... \" H... .Al..L.5...-... wiHta1 F/rluJ'"!.Name" Z. A. rb~': \ r",""? DIoIIl' 11J/.J.1J!.0 ,~:_, ,:,. .~'

UNJVElt5IT~l""~D.\TT.N. IolAGN£TICS LAaOJlATOJl:Y ,.,

, _...-,'.:

....

,.

...

......

" .

L ••

I·

..

...'

:I:·

......

t ..

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,

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•

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•... J....

•....... i

......c•... , .."

L_.,...

I.:

.

..

.,

:

.

... . ..... . '"

: .,....., :...

.. ...........•....

......+··f--'·f····I.··,· .. . .....•.,,-'

.

!Ui )!!J1!j::,: :':

!':I:"

>I»- " ..-0

:..- .. .. ..

:2

H·....

".. ,. ..

i ... .....r'c ., ..

:,.... ..

I'" .... .

I.. .

•••

'"

...

. .....,.... ,

i" .:

oFIGURE 27 Major Hysteresis Loops For Cube M-1646 at +150 C.

\J1o

j,:

,"

,

.

,... I· .. ; .. ' .C

.. .-

.. I ,..

,. ,~ .. !."

''1'

i!"

I,,, I.. ·

"

, ,•-:'

'[[.. , .i i\ :

:j.

I" I

=(i~l~J[.. .,.

I·· :' c

.eo,.! :: ...

~.~ ,'" .C , :

,-,-, -,. - .._-.,.,

'i, ..,. i_.... l--., ;...

... 1-- ,

"-1,', ... ....1,1::::

. , ... "

c," "j .. cLc [, ...1" I c,

j'. I 1;, ~,

I., :';.- I .. I.. ·

.

.. ,

....

.,: ..

..

..

..'.

!

FIGURE 28 Major Hysteresis Loops For All Three Cube Axes For M-1646 at _SOOC.

:1

I--11ii

"! ,"" \

kA r Il·)!t! (t</tl~( H~·: r','dl:'~

N• ..,. .-l~_~QUNQU~~=lINlv(:lItSfTT OF DAYTON. 'J,(o ... ~'·-'fl'·

,.....,l.Nnti~ ....u.lal. M~L.jll _

~"'-' J:1dL>JLmILSN,.: .£.u,b.e....--.. .....: 'N.".tJ. ",._~,::

W...nl;-==....J V• I : --.,,,," p.,..,.:<y

S....,I. Ne.M:L~Ma.~.;al: M~.,--~~~I_-~C~__,-".1MlSUSHDlL ._.!'I"-I"" -.-G.Q~0t1n:lft0314/(,.d 3US~,il'i-,Weicht: -==---- Val, _ c",J "'"... lly: - lIe..,!

,If". WJL.O•. •H e • _-=---e.. -r' ..b..Q.L.LcT::(1°c..

"HlM • =."""'- ..... =- 00 H_ A_R.Pu.( Co,'........1... 11\ H

II.~~_l..._lco. Wll1t4t FIx.1"()r~

~m. -.3- A_ m!li{o:~~._.,.I~Vi'()tlNlVEa.TT~!t~. lJ"''SN~!CJll'J:i~.fl~TOll. y"

U1......

FIGURE 29 Major Hysteresis Loops For All Three Cube Axes For M-1646a

at 0 C.

•• ,.;

!...•, .. ! ...

H·I,

J:!..•. .:....••............ . ...

•••

.• ••

..

,

'.' ,

.,

".

U1'.

N .:...

. !...

i.·, .....

. 1

" ..•• ! I',

i I',

,.. , ::"

,c.. ' .. ':"...

...... I.. ,' --

,

....

oFIGURE 30 Major Hysteresis Loops For All Three Cube Axes For M-1646 at +50 C.

"'j""

i"I"

.....·1 ..

.

I,·'.'

,

,

.. '. .,.. ~~: ,,' ~ I

I'·

·

·

I i I

i

I·

I

i, ..

i

....

I... ",.+--...-

I'"

..

I,

1.,.',1,••,.,,1'.-1-'.1·"'.1 ....1',,+ ·y·'··r'-f'+ '1"',1'-"'.1 'HI...++h+ld

,,;;Jpll0'r il! ,,/:,"j' ., ......~~I-'" .. 7: .' •.... ;H"+'I,-+.·~j-"·+.+-1-"1'--••.+-+-~·-lc4d-++TI:!P'M··+-+.. ++-:-- t~t:/f-j- t-i--t-·il-l··..r"I_,;;.t-I;;.,""""'If'

I.' .... ,.'

,.f-,'··~·r-t-t-+·r·7 ....t-+·T·'· 1-.... ­!~L ~. II ••

1:.".L+... +•. 'ICO i"'"

FIGURE 31 Major Hysteresis Loops For All Three Cube Axes For M-1646 aat +100 C.

........

....

.. ,

.

..j ..

.. - .

,

wMc: "1lJ.!k..o., .Hc·--.::::::.....-O•. ar " [.3J k.ci::/S--CDc..

""'m' =-..MOOo, .... -=-.. ~. h ()~4f too'(....•••lis... \- H,I •~k" wi f1ttd F'1.1lJr(,"'mo' ,.. "D£L"'OU~ .,., I12LlJ.Pi>UNtV£••TT er .AYTON. ),lAGNElfJcs",""aAT••Y

!

. ...~: .._c !.--.,. 1---,,-+,--,1·· -----', ·e-I-+·I·.j--·+-·-'- -IH..,--j

-lj-

1.. _·

,--

1--"

i

.

.

..

,-- ....

....

--·f--'·

.

..-. _.._,

...

.

---L C- .- .... i_.__ ~"

, --.I

.... ,.,--

... ,..

..

• j ... ", ......

..

..

. "

III"

I·

;

:

.

.....

L

,., •• t ••

...

.

H'--'I~-+·+·I ... i·

.. ' .

~- .--

..........

f";+-+-,--Ic-+"'l"+-,.+--c'r-+--+--~--+-+---+-i"+-+---I----"'-+---r'i '-+-~.'-i---"i"--'···l--'" '-1 ,.k".iq,--Hll-I+I-I+ :li·II·", ..,!.

FIGURE 32 Major Hysteresis Loops For All Three Cube Axes For M-1646o

at+l50C.

2­-H["OJ

, i . -- e.. if-

iSam.l.N•.~""'I.r...1 Mdl-C.

.~ iAM~rsvmr" !--,-- .._, ..-Seurc:.:

~,.: G<lIoe. ....., w=O.31~ h~o vq P~onlW."Iu:~V.I: - crn

J0.••." - ,Iem

,f-

~.' ~ i---

.tt".:J.JH ... •Hc·~o. • • r·6~11 Ie co .. ..

T~ ·3"O~c...

~, _. 1- ~-I_tit.. '~WOh, l\t • J·!tt 0. S.A pvt.. C.// .. _+_.

i........11".... H, 1 ~kO- Wi H~..1 F.j,flJ'~_.z. A ....PE! NO!II ..,.:OCT l~ ·W~ .. f~'

v.~~ ....

uNlv£aa-l""r kTTeN. WACN£TICS uaoaAT••" . ..:j, - I·· i- 1-- j-- 1-- .' i-.. ,_ ..

.. .,.--- . ...

j~.

Ij~!_'- ,-!.- 1·1 \ .. ,f !

i·-....

!/ 1-· I: J2 (i

.-.-. -- '/ '-"---i-'

~,I I/V i· ..

I!...I·' ··1· ... J._ .. .... , .. II/I· I 'I ~. 0.-

1/'j\- .. -1.- ._f-'- ,.-

~j[.

···i ... 'ii/ .... I7rJ .... i., i f-, i.-t; / i--I~' 1/ u. i ) / \/ I

~ ..I· ... l- •• .. I.. '.! .....

I /, . . .. :!j

I I·' i.'I .. ,- I··1- ... i·-\ ..r/ ..

.... ]

/ I,· ,._- ,.-ifIhV' ..... .. ,.-. (ll I·..... I·· i-

1·-- 1 .. -'--·

I/J!II I I ViJ 1/I.. ·i .. I·· 1,,-,

Iii) j(- -'(I

1.. 1.. 1/ 1-1-·/ I

2 - .,.i II VV ViI.... . i- .

I t - 1-,--·.. Ii/[.·,,1 .. . ...

VII! I ...

II

i ,-. 1-- ,--

1/ '-IJ ... I id'ill I I,!/,I !- ,- I...... ... >--- 1-..

V!j 0i VV I··!·,

, .. t j _.;-i--

~il~f/, I / V Z.... 1\··

..i+- f-- :)If-- !h

!-'1---

i V'tw i·- i I", _.~_..

rl 0f.. )7' ,II i--' .....;. .. -

! i,

i i, ...

oFIGURE 33 Q-2 Recoil Loops, (B-H) &B For Cube M-1646 at -50 C.

..

.... , ..

.

!

~I1I

I,.I,'·I-'!',!', ,

1_1 :

'. / : ~/' ~!,) 'I ',I·"I""!,--·"'··!

.. V

•

,

I'

1---- __ ..

1J'!/ I/I/!)II

.'

I-~-;-'e-L,:

...

;

I

'+,1-- ," I'

,

....

l-il--+-+I-,·++-II·I,II,A'II,J..,..r1(\1 f'!-9V 'j ,(Jfl"

, i

I,",! .. ·1-,·'],;,-1'-'1 ~l).. I,",;j.y"lh~"! I LV 1/

.' fl. ~I----~k':--I::/-I·''+'•.,.·I--,·II·,.L,·...+, /- '(.. IZ'

I·

I'

sa.m"I.N.~wmr"l Mn-AI-C....... MHSQSHrr~SN... C,,»e.. D1m~ ::0.1/" "~0Y91.0:;;1

iW.i&"t: -=-.. V.I: - cm) ......Y: - licm}

wHc·3,02to•. _Hc ·2,:)j/c:o.'-r' 5;?OJ(c

I_H).. ,Uwce.· ~ .1.3/to., JA.OV~I c./(...1 "" .. H,.~Ir... tfJ!Hdt.iFirtlJ/le.

Ha : Z. A. AIOElNO'I'-' •••: OCT 15 '.0 _ --:--~ ;._ i- ...=Ea~A~"''4iA'a••~I•• LAaO.ATO.Y f..:~

'~·I-·-

...... i , .---

--,--

:I ",.

",-" I

,-

,.

I+--+"'!'.".+~--I--.. I'.~-I ... 'I--'J·,'

l-.,~~!,// I

I~!- -~~Y; ,~ ,' .... j .. ".~_ ...I-_L

t~~-I·-+c+--~j---'c-+-·,-+-+--,I----f---l-- -1~~k-+ --1~ ,- !--t~ I/J

1;-I+I~~+I·f',_+,+--j~+-+--~j--I--~jl--·_'+~~k~~'c4.4....j-;I'" ,,- - l7 iI I~ 1 .,.V I/-!l'.. v,'fl·

,:It 019f--~~ (LiAV

FIGURE 34 0-2 Recoil Loops, (B-H) &B For Cube M-1646 at OOC.

f-- , \__ +__ -1- _,i __ i'T

I-'

_ 1

I

• Ibl

i I~·l

T--I+li. 1-'1- I

~--I+-l:-I· ,.j. .. , ... :-.

·j--_I f_--I'I-.:-tl'l"1i--i-l-l

1~-J Jill·tj~_jj_ I

---]~,_·h~l_i,-rtl-'-III--YA--+--t-;';}l+ .-'1 J-

-~I'll--+I'111.1!,

I IiiIi'

I

.J4c·~' .Hc ·2#2/k ... •,.~c

""m''''?'''''' ",,-I,R'" i;JOp';.,,/G~:(.......h H,'~k" Wi Het:l.1 P,',r"reNun.: 2 ".OELNOUft .1.: ocr 2 1 ".llUNJVEJlSlTY "j\~JY~L.4i>l<l~i~U.TO.'l

---+-

---1---

.--

f-- i ---- ---+---

-,- -i

1---1--+,--"-

U1-..]

oFIGURE 35 Q-2 Recoil Loops, (B-H) & B For Cube M-1646 at +50 C.

·.,1··

., .,,: ,

I

\.1lj'

00 I··,_.;......

...-;-- ..... .; .. '-

. ' ,

,

_........-- 1-·, ..

...

...

...

i,

' ..

.'

.

.

·1··

s."pl."-.~""tni&l' M•. AI-C....'00 MmUmra ......... Cube ..... wll l~ 4~ail4 tawW'''IrlI:~ V_I: - ern} ....It,., - II"...}

. ..

.

FIGURE 36 Q-2 Recoil Loops, (B-H) & B For Cube M-1646 at +lOOoC.

. ..

.- ...

.

... _-_ .

.,_. .

- .

,. . .

i,

I ,.

T-' +"1'+ I· +.\.. c·!, f···

1---,.. i

!

...

.. ,_ .

...

I·

··'·i·

.... "+'+"'1-"

.mpl..N•.~t,":ri.&l: Mn- III-C.""00 MATSUSHITA~,..: (/o'\ae atm:Ul.Q_3(~h.O w~ '.(1""Tz./We'lhl:...2....J V.I: --- em) ....11.,: - ,Iem)

. ·,·+.·,1'''',+,'1···1 '1··!'."I'·'·I.'·'·+c·,H.'·"·H""·+'''·I''-I,I'II.\,MfJ,""1"111 / il..'. .. h J VI .....

\ .•1-..+-+-+.. :... ···._+'-+,++-+.-~-.f-.+--Ic+4+-+-c++.,f-'1,-.i. -t_\-~tf-IJ /.~J'.. "; ... .... .,' ... ", //if .i!J~(j

.... 1 T .... "', .• '. •..• W1/~0._...._.. __ .;. !.J ~

... '~/f\,..... ·····-·'·--r All-V, .' fA' .

· ". •.. ./1' 12 i,V:' .

'i A0,11- .... , ... _ ...

I -1-JnOa I

.~.

_ .

..- .. !

...

_. ~i-·· _.

. ·1·

. _..

-, .... . ...

1

·1.··1'+'+1' ....H'-i-+-+-+--~--I- ..

i'·· I..

.. 'I··' ••.•

t+·L·!···J.',·,·+··!.··I...

··_····,·I··-\' 1

"""'-,

.

'.

-­....

···1·+ ··I···+··I··+:_+·+·'·I~··I ··1· I I ..

....

.·1

....

-"-' -­...

..

_... . ...

..

i-~--··'

1-·"'-

FIGURE 37 Q-2 Recoil Loops, (B-H) & B For Cube M-1646 at +150o

C.

~I

....

... I···

','.... !.

I··

···1··

..I····

..... .... '';.

i·J

0'0

.... _.....

\.

,

i ... j ,..i! ' ....

!

I

•. it.

uo

"'T2 -H[We]

,I !I ... ",. i

, i" :

........ I··, .

~'i

;. . ... ..··1··! ... ;'"

.. '

,. I....." 5:

)~~V.. .....

I,·· i 1···I···j·i

,...

i.... f- I··· ! .......

.

~llV'.

... . .

.~ .. '

,·1 .. , !. V, '! i I I .. : ..

i/l// V" H

+

I··,··.. I) ,.... . ...

i .. · .'Ff' .. '"

f- ,J i... ~1

i ..

: , ...... .,,! .. Jl'4l /... ....

:'4

... -. ,.,...

. .. .,'" " .... II .. . ......

... !.."

ill ' I .j ," I'"..... ill !)I-.I~, it

iII il'

i .. ;

U ',' ,......

't/II..

r;/

... .

...

; ... .... -~

/;,U !.r .- ..• ;- I··..· Z: .

.... II Ij I' :/ I

...1 ...

I il ()' ,.i 0 I ... ,......... ,.. - .

'01: ':;:! ,

't..

U.. c i

'0 ...., - f.,.

;.;~Ic

c

! I !.. ' I.. ·

i u;"

I

i

" "'I .. 1-·

1/Ii r

,,•

3,

,..,•.....'

I i

FIGURE 38 Com.posite Q-2 Loops, (B-H) & B For Cube M-1646 At the Various Tem.peratures(-SOoC, OoC, 2SoC, SOoC, IOOoC, and ISOoC).

,...- ,-- ,T ~"T'

( ., .. I·· ..•.. ...T,. ... ,. I .. . ... ; -- -, .- ,...

", .. "

I ,.. I,e ... .. ,. i···: ,...,,+

, . , ..i·

.. . " . ~~.~j

.... •.... ,.... ,-~. ". ··'·1·'" .., . .. , . ...

: ,.I- .. C"". , I '1-'

c.. ··,·· I",. .. ,..

II,·"I

•••I.'

I I···

I··· ,. i,,,' .,' I,· ...... ~ ... I ,.. t,. ... ,.. :.

"':+'~,....

L ...",!--. ifr:k ...- ;;';;,

~ ..... ·/1.16I .. :::-,'

kC::':I' , , - r-

: .. , , .. .... ...

.'./ ;'

...

......./'

I •. ~.5 .... , ..

I.?r; ....

f· ...- ....

il V )1 i.. .,.+ .. I·· i·.· . ,. ... . .. , ., / 1/.. .. ' ." . ,; 1".0\~ 1/".... I, .. ' I, ... / , .. ,... -I .. ~.~ . .. _.. ... ... I ,'''' i'" . ...', ',i'

I.·· .....' V ... / l/ .,... ....

~7V, , .. ....

••..

II / r--' 1/.... I·S I .. ... ...

~

__ I-"".....

.. ' .', '.' i ,. ". , ....

'· .. 1 if ...... ...-.,. - ,II....,I·' ':'i

... 'r ?... '...... fe. I .. ,

./"7

,'.' tiJiL i",

.ee .. _-_.... ~.- '..I ,.,'i' '., rt.:

/t.."

.,

,

."

! ... ... ... .. .. I ..

._.,- ' 'i, .. ,_ ..

• ••..... /

... .... .. .. . I .'.,. -. ,. ....,.."

,

. ....

:..... ....

' ..... .... .... .... i " ....... ....:/ .. ' !

...... ,.k~.'.N.~ ......"', nn -fl/ - C,.

/ J ...'<" fttlTS(JSfi/ [.4-_. ~+. !-r1/..

i.

5_,,",: Crt",d,.( .....,d~ooz.r'·!R; Om- I

/7'/ _1

... ,...- .. , .. :.. - ....w.....ht: ---=-..I Vel: ____=_5rn' ......y: -=-.1"") . :.- , .. __ .

./ .lI".~.•Hc·~",·r·~Ci, ..... - _..,... . .... -T . ,.... ... - .. - _. ,.,,,,o'e:" . . -""--,< (.H)•• i:l-woe.. I\t .1.a...4. .., T; 25°C

-,,/ ...?

,......t1"oIIaH,_~......

"i._' : :•.. ,.-- ..... ..

.~.! ,.-, ...

•

.. :.. ... . ... Hal'll.: 2Q«1 n,U'· A-t$t)!£LN()dL "1.:fJ2L1:!t11.0

: !-UNlVJ:••TT er aAYTeN. WACiN£TtCS u.e&ATUY

'- i ! " : . , . ..

•••

.-- - i.... . .- ...

,I

:.....

,.... ... ,. , ... -'i .. ,- .1 .

... "1=-..... ... .. .. - ...

I i i'" T... ....

, :. . , . .....

'i.... i"

..... ... . ....-

I....

I ....-- .... .-

'J!..

,. I , ..... ~.I .... _.-... .. i I I

FIGURE 39 Major Hysteresis Loops For Cylinder M-1642 at 250

C.

_... ... r' .. ,- --I-'- "T'-' , ..

I.--

,I··'···· "I·· :

... :___L.. ... -. ... I· ..... c .. .. .... , ....

"," i·c·· ... .. ,. . ••,

' ..

;.'•••

' ..-j- . ... -

(I IJ.l !L," i·-·· i'-.... ...

I . ...... I·: :.. I·

••. : . .... _....-

.. I ... ,lk'P,,)··t·· ... .... , . ...1,,-,

••

... ..I

... , f-- :....

"--

I··. , .... ,.

I· r-" ,.~I-

.... ···1---.. _I-'

l"rYll... ,. ,...k i"~

• 1// ....

'r.... """ f,-. ".-' :,-... ..... ,.lr" ./- -4 .~ ...... ... .,' .<: .•. i.'" " . i)./':. "'C' I"

./.. " ...... '.' i·

f21/ ,/. ... :... -!--.

Ii,'" ... I·· .... •I." ./ / 1-----

...

,~i ..... I.. ' ....... I··· ......... ....'

i·' . J,

( V,.-,...I I !/

-I If 1/

C"'".. ...... I .., ..... ... I ,.,.... .... I.. · I.. I'·'!

'iJ i'" .

f II ... / ... '·-1·.. ·-

•••• ,-1",~5., .

I' j ,.. .. .. I......... --

," f ~\ '.' J'+.e .i. ,... ,. (.- . ,.. .... .....I .....,

••.. ..1... .. I I . ..... .'."

.. ... 'U'" [,u ILl 'J.... ',' ,

-_ .....- .~.... ...... J ..... ,- ...! .. I,.. ... ...

1/i· t-. .

... ...... .. ,.....· .. 1 .. ··

.. ' . .

.I . I ,

\

.- .. . ...

'.' 1 ....-. i if .. i.... · ... i·· .... i.. ... .. .. !.., .,. ...

f· .. 1·- I··· ,.... .... -' .. .'.' ...

... / ..... I· • I·· . ' .... .. ,...... ......N.~...., ..,. (1". AI- C.. .. ..;- .. 10.,... tileTSU,HI f4 . ......

,/ I·,· ...~: CftMl",,' ..... 0/:0,U'16 -d.o-:ZZo•

/- W·llh1: -=:=..J V.I: - ",.,3 ....1IJ:- I","n,,. i· .• ,.-. ..- 1··-- .+,- ....... 1,-, i···..· .

.. ..- i.. / M.H".~....H".~O•••r.~C

I .. : I/'~' -r":

.... '-1-,·· --- - i i.::: >-L- ' .... ._. I'"'.·li......... . /~kOo. ':2S'C. .....

, i'~ I .. !.L !,

,..... / ....... e>••• iIo H,-'--k.!:i..-.........~... .-" ,-'-

...

,.-,-'- :... ,..... ··1-- ..... -- .....,2ecdtlc< A4/J(n..AJ0cJ~ .1.:~o ,....--,-

l-- 'r~: !.. ~U.TY er hYTeN. MACN£TIC& UMaATUY,...-., , : , ....... ,

. . ....'''- - .... .. - ... ,..

~J : --i .. · i·· . ..

,•

. ........

L,.. ... ...

i! . I .. I..

-- - .... I··

J_.

: r':

"'1-- 1--·

! .. ,. ..,,--- ........ . ,. .. .. - ... .. ,--.

I• •

, :.... .... ,..

C... 1 , , ....... , - __ .l -- -- .. - ,

FIGURE 40 Major Hysteresis Loops For Cylinder M-1643 at 2SoC.

, -

'-

1'-1---­·-1-·

1-

,

-

T1--1--

,-.,-- , ,----

I-I 1- _...

Ii

•

II'.'

, 1- ! -

I··

----e·,

·fI I

i ..i

!--- -_.

L __ ' ___ ---- I ..

I

1--

:

I·' I·

I' ..1--1· IJ- I,, i. I I-

I i

!-i

I ,

.

M.....: 2e,Jhr,r- A-dUffL.AlIJJ,e .,.:~UNIV£ItSlTY 0 ...ATTON. WAGNJ:TIC.s LAM.AT.aT

i

"m.'•••.l1JiJ;!;••"••a" 11(1 _ ,4-1_ C"',,., tjATSU5!'!lrA...~. Cr/,ad!/ ~m, ,A=O,Ziltr'~e.()-3tr _ ,__W.IcId:...==:......JV.1: - c"'l ....It,.,_ .'e... ) :::

yHe

•~o•. •H e •~••. a r.~o

,ON)m·i,L.-.- "" .IJ5k~, ,; 2""C

,

i

... ,'.,...

.1 1 __ 1..

.'

,i

.

,

! ",

r--

! '

...

, ..

.-- ,-- ,--

,,

,- I 1---

t -c- _i __ -I-__,,_+_c+__ ii _

,_,i __ ,__-,_..L .. , ,-.. _. L

,,

+--1-- ..

;--- 1--· "--1

_ .. 1_- f' I--I 1/

f-LI .--- t)/iT- 1--

~L,/' ,

..'- ,

,

....

I

•

- I

1.- 1--~--

!

.-I

··1··... ,. 1- 1-- -

. :

,--I-

----- 1--. 1--- -.--- ,! .. .

. ,--. -'."

-- .... . ------ l-- _ .... I-i... -.

..

-.-- 1----- I ..

- ,-- i __1

Ii i

,

I-I",

Ii,

-I I

i

I--

I i

IT C--,--­

'--I-I.. i,

f-- --I--'···+··~I.. !-c·--f- -1--; -+c-r++'''~--'''--I'---''­!

.

···1·---

I1-

- ,..

, I

1-'···

.

,

r

FIGURE 41 Major Hysteresis Loops For Cylinder M-1644 at 25 °C.

,~. ,..." ·T"· . "

J"~ "" .

\... "

1 IT"..." .

iII ···"·'h~ ". I··· ,,' I ... i- .. .,.. 'c . i"'

II.•I·";" I. I··i·· .... .. ... ··C

·c· ....·c·I··c, .... .. , ...

I·

D)-~) !~,... .... ..,.. , ~. i··· .." ... ,...

I ', ... , , \ ..- .. '"" i~·t- i·· ': ... ....

"... i .. ' I I, .• , IL' .... I··... ,< •

i'" [

i·· , .. .+..,. ,," ... ,1 ...... ," .... . .. I·i' " .. "

I , I."1-- .-j- ~·r·"· ~""". .... ,. ,~ , ..;j:;' ,. J J i"· , - B \ .. .,. - .,;1; ! e::.:,•.. -' f. ...

, I" ',1"

fc ..-t-"::-r-:-- .. / I··: k "",-- '''l> i"'<' I ,.. ' .. " ....". C'

!~,... '1\ L~'.... i

: ,. ," '-' .".~l /- .. - r , .. /k' .... ,. ,/,,' c ... ''',,. btr~

....1·+ .". ./,·c" I'·'··' I II ,

)' .... ... .. ,,' c1·-·

.'' ... of

+l~tHfoil~ . l/I ·1· .. .. ..... - 3.tl ,.... [.,' ·.c···· V .. ,

C·",.. , ,.. ·'c "

..... ,.,-~~, .... ·c· [I If ., i···

I··,

I I .. ', ...

f.... ...

r-. "._-_. V- '~ -Cr" -_ ....

.. ' . - 1.5 I., . ,. i' ." .. '".... ,.... , 'e. ,. ...,

!/ .. ,-~I"·· ........ .. -- --'-'- "~ _. ,". i·"- C_, .. ,.

" fl'. II.1..1. """I ·····c·· j - ,•.......,"" .. ' I ...• ,..... ... .... .. ,. .. '.'

1"" "....

.. , '. !.,., [.: J I ,.'·k',' .' III ~ II. W, '~, [ r .,.

... l' ~_c .' ... ...

......'"

••

····1 .... ... .. ! + . ......

... -I-- I"·· iI , / .. I······ .. . I. ,.

I ...... .I '.' ... ,:;'... ....

/',... .,. ..... .... ... ....

I·· I' ' ..·C.,. I····

...

'.'... , . I ). .... Sam........!1:Ilt!ti-.tU...I' tia_Hf-C

,.. .. ..."., r1/fTSUStfl TI4 -.,.... ... / sa....' Cytade,c ..... d;o.zI({fT-I_o7'(9¥

1/i··· I . , ..

!/, ...

... i'- I W."W: ....=::....J V.I: ---=--cm:t ..... it': - lie...,

._. . .

/f:"" ! ,"I ··1,/ .J'c.~... •He*U1t..o..•t·~G·'.

1··.. [·· "..../1/

"

i""··· -I· .... I ..

~--"l.....~..... "" 0/21.1<00, T_ 25-C. ... ...

.. ..-r-- .. .. ......li.eoIlaH.~~~H-·· --, .. --' \.-

.......I··· ..··1····· ... \ .. , ,. i"' i·" I··' ...... ...+ .. ... ..Na••: 2'0";'''<- !l1S!JFLtvtJV..e.I .' !J2il!I.Uo ..

, ,

iUNlvUaTY er bYTON. WAONJ:TICS J..U,()&AT••Y

','",- --

r ,.,' i,.." _... . I·'· i··· I··· ,." .... ,.... .+ .. \ - \ ..... i···· , .... ..- .- .. C'"· I'·'

.'

,..

! !.

'[ ,,... II···· .- i· _..,- ..+...... ... ,.'.. ,' .- "

. , ....,

:

,.. ...

,

'r-+"i, ,,'

I.. ! [., ,. ," .. I·· ;. .. i·· ..• - •.. , . . _,

!,.. ... ,..

.. I·,··f····· I·· .... ,.. . ...

. 1 i,

I il_,'_.~ . L . I.... L."'. ,.....•.•. ,-- ... ....- .... .

FIGURE 42 Major Hysteresis Loops For Cylindero

M-1645 at 25 C.

SYMBOLS

B

H

M

(B -H) = 4rr M =Bi

Br

H c = BHc

MHc

(BH)max

fJ-r

Tc

d

HRc

Bgap

RT

Q-2

Q-3

L

D

APPENDIX II: LIST OF SYMBOLS

NAME OF QUANTITY

Total Induction or Flux Density

Applied Magnetic Field

Magnetization

Intr ins ic Induction

Remanence or Residual Induction

Induction Coercive Force

Intrinsic Coercive Force

Maximum Static Energy Product

Knee Field (Hwhen Bi =90% B r )

B at (BH)max

Hat (BH)max

Permeance or Unit Permeance

Permeance at (BH)max

Recoil Permeability

Curie Temperature

Density

Electric Resistivity

Hardness (Rockwell C)

Recoil Ener gy Product

Gap Flux Dens ity

Room Temperature (,.,25 0 C)

Second-Quadrant (of hysteresis loop)

Third-Quadrant (of hysteresis loop)

Length

Diameter

65

UNITS

Gauss (G)

Oersted (Oe)

(emu/cm3 )

Gauss (G)

Gauss (G)

Oersted (Oe)

Oersted (Oe)

Million Gauss Oersted(MGOe)

Oersted (Oe)

Gauss (G)

Oersted (Oe)

Gauss/Oersted (G/Oe)

Gauss/Oersted (G/Oe)

Gauss/Oersted (G/Oe)

Degree C entigr ade (OC)

Gram per Cubic Centi­meter (g/cm3 )

Micro Ohm. Centimeter(1 0-6..n.. cm)

Million Gauss Oersted(MGOe)

Gauss (G)

Degree Centigrade (OC)

Millimeter (mm)

Millimeter (mm)

REFERENCES:

1. T. Ohtani et al., 11Magnetic Properties of Mn-AI-C Permanent MagnetAlloys.1I IEEE Trans. Magnetics, MAG-l3, (1977), p. 1328.

2. T. Kubo et al., "Anisotropic Mn-AI-C Alloy Permanent Magnets can beMachined and Mass Produced." JEE, No. 127 (July 1977), p. 50. (DEMPAPublicqtions, Inc., Tokyo, Japan)

3. M. A. Bohlmann, IIManganese-Aluminum for Permanent Magnet Material. IITech. Docum. Report ASD-TDR-63-422 (1963), Wright-Patterson AF Base,Ohio.

4. A. J. J. Koch et al., J. Appl. Phys. l!. (1960) p. 75 S.

5. Y. Sakamoto et al., IICrystal Orientation and its Formation Process of anAnisotropic Mn-AI-C Permanent Magnet. I' J. Appl. Phys. 50 (1979), p. 2355.

6. G. Y. Chin et al., II Impact of Recent Cobalt Supply Situation on MagneticMaterials and Applications." IEEE Trans. Magnetic, MAG-IS (1979) p. 1685.

7. The Information about Matsushita! s production program and future prospectgiven in this section is based primarily on conversations with two Matsushitaengineers, Mr. T. KuboandMr. Y. Sakamoto, in June 1979 and In May 1980.

8. Y. Sakamoto et. aI,,' IINew MnAIC Permanent Magnets Exhibiting Macroscopically­Plane Magnetic Anisotropy. II IEEE Trans. Magnetics, MAG-16 (1980) p. 1056.

9. Matsushita (National/Panasonic) News Release, MEP-77 -7, dated March 4, 1977.

10. G. Kliman, General Electric Comp., Corp. R. and D. Center. Personal com­munication (July 1980)

11. P. Campbell, II The Magnetic Circuit of an Axial Field D. C. ElectricalMachine. II IEEE Trans. Magnetics, MAG-ll (1975) p. 1541.

12. P. Campbell, "Permanent-Magnet Motors for Electric Vehicles. I' ElectricVehicle Developments, No. 3 (Sept. 1979) p. 1. lEE, London.

13. F. Echolds, Garrett Airesearch Mfg. Co. Verbal information (May 1980).

14. R. E. Joseph, 'IBallistic Demagnetizing Factor in Uniformly MagnetizedCylinders. II J. Appl. Physics, ill 1966) p.4639.

66

1. Report No. I2. Government Accession No. 3. Recipient's Catillog No.

NASA CR-1652914. Title ilnd Subtitle 5. Report Dilte

TESTING OF THE PERMANENT MAGNET MATERIAL Mn-AI-C March 1981FOR POTENTIAL USE IN PROPULSION MOTORS FOR 6. Performing Orgilnization CodeELECTRIC VEHIC LES 778-36-06

7. Author(s) 8. Performing Orgilniziltion Report No.

Zouheir Abdelnour, Herbert Mildrum, and Karl Strnat

10. Work Unit No.

9. Performing Organization Nilme ilnd Address

University of DaytonDepartment of Electrical Engineering 11. Contract or Grilnt No.

KL-365 Magnetics DEN 3-189Dayton, OH 45469

13. Type of Report and Period Covered

12. Sponsoring Agency Name ilnd Address Contractor ReportU. S. Department of EnergyOffice of Tran~ortation Programs 14. Sponsoring Agency ....Report No.Washington, D 20545 DOE/NASA/0189-81/1

15. Supplementary NotesFinal Report. Prepared under Interagency Agreement DEAI01-77CS51044. Project Manager,Francis Gourash, Electric and Hybrid Vehicle Project Office, NASA Lewis Research Center,Cleveland, Ohio 44135.

16. Abstrilct

The development of Mn-AI-C permanent magnets is briefly reviewed. The general propertiesof the material are discussed and put into perspective relative to alnicos and ferrites. Thecommercial material now available from the Matsushita Electric Industrial Co. is describedby the manufacturer's data. The traction-motor designer's demands of a permanent magnetfor potential use in electric vehicle drives are reviewed. From this, a list of the neededspecific information is extracted. The results of measurements we made to fill the informa-tion gap are presented in the form of tables and graphs. The data is discussed and interpreted.The tests determined magnetic design data and some mechanical strength properties. Easy-axis hysteresis and demagnetization curves, recoil loops and other minor-loop fields weremeasured over a temperature range from _500 C to 1500 C. Hysteresis loops were also meas-ured for three orthogonal directions (the one easy and two hard axes of magnetization). Ex-truded rods of three different diameters were tested. The nonuniformity of properties overthe cross section of the 31 mm diameter rod was studied. Mechanical compressive and bendingstrength at room temperature was determined on individual samples from the 31 mm rod.

17. Key Words (Suggested by Author(sl) 18. Distribution StiltementManganese-aluminum-carbon Unclassified - unlimitedPermanent magnet STAR Category 85Magnetic test results DOE Category UC-96Propulsion motors, electric vehicles

19. Security Classif. (of this report) 20. Security Classif. (of this pilge) 21. No. of Pilges 22. Price·

Unclassified Unclassified

* For sale by the National Technical Information Service, Springfield, Virginia 22161

NASA-C-168 (Rev. 10-75)*USGPO: 1981 - 757-072/3202