EFFECT of ADDITION of SOME RARE EARTH ELEMENTS to ZINC ALUMINUM ALLOY ZA-22 on its METALLURGICAL

and MECHANICAL CHARACTERISTICS

Adnan I.O.Zaid, E Mail: adnan_kilani@yahoo.com Mechanical and Industrial Engineering Department, Applied Science University,

Amman 11931 Jordan

• Zinc aluminum alloys are versatile materials which are widely used in manufacturing several parts in the automobile and aircraft industries.

• The effect of grain refinement of these alloys by rare earth elements on their mechanical characteristics is scarce.

• The equal channel angular pressing is relatively recent method for producing severe plastic deformation in materials subjected to it resulting in refinement of their structure and enhancement of their mechanical characteristics.

• In this paper, comparison between the effect of adding either titanium, (Ti), titanium+boron, (Ti+B), or Molybdenum, Mo, to zinc-aluminum22, alloy, (ZA22) on its metallurgical and mechanical characteristics in the cast condition and after pressing by the ECAP process is investigated.

• Zinc aluminum die casting alloys are widely used in the automobile and air craft industries in manufacturing many mechanical parts e.g. carburator bodies, fuel pumps bodies, wind-shield wiper parts, control panels, horns and parts of the hydraulic brakes. Furthermore, zinc-aluminum alloys are used in structural and decorative parts which include radiators, steering wheels, hubs and instrument panels

ECAP

Materials, Equipment and Experimental Procedures

Materials

The following materials were used throughout this work, namely: pure granular Zinc and commercially pure aluminum, of the chemical compositions shown in Tables 1 and 2 respectively

which were used in manufacturing the ZA22 main alloy. High purity molybdenum, titanium and high purity aluminum were used in manufacturing the following binary master alloys: Al- Mo and Al-Ti

Table (1): Chemical composition of Zinc Element Pb Fe Cu Al Sn Cd Zn Wt % 0.003 0.002 0.004 0.005 0.002 0.002 Bal

Table (2): The chemical composition of commercially pure aluminum

Element Fe Si Cu Mg Ti V Zn Mn Na Al

Wt % 0.09 0.05 0.005 0.004 0.004 0.008 0.005 0.001 0.005 Bal.

Experimental Procedures

Design and manufacturing of the equal channel angular pressing die, ECAP.

• Preparation of ZA22 base alloy

• Preparation of the binary Al-10.7 %Ti Master Alloy

• Preparing the binary Al-6.47 %Mo Master Alloy

• Preparation of Different Micro-Alloys

Mechanical Testing

• Micro hardness measurements

• Compression test

• Equal Channel Angular Pressing (ECAP)

RESULTS AND DISCUSSION• GRAIN SIZE

Alloy

Grain size (μm) Before

ECAP

Grain size (μm) After

ECAP

Reduction %

Pure ZA22 26.96 15.1543.81

ZA22-0.1% Mo 18.75 17.28.27

ZA22-0.05% Ti-0.01% B

14.6 19.8

-35.62ZA22-0.15% Ti 16.1 15.2

5.59

GRAIN SIZE REDUCTION

BEFORE ECAP

AFTER ECAP PROCESS

0 0.1 0.2 0.3 0.4 0.5 0.6 0.70

50

100

150

200

250

300

350

400

True stress- true strain curves of ZA22 and its different micro alloys in as cast conditions.

Pure ZA22 ZA22-0.1 Mo ZA22-0.05 Ti - 0.01 B ZA22-0.15 Ti

True Strain (Є)

Tru

e S

tres

s(σ

),M

Pa

0 0.1 0.2 0.3 0.4 0.5 0.60

50

100

150

200

250

300

True stress- true strain curves of ZA22 and its different micro alloys after ECAP process.

Pure ZA22 ZA22-0.1 Mo ZA22-0.05 Ti - 0.01 B ZA22-0.15 Ti

True Strain (Є)

Tru

e S

tres

s(σ

),M

Pa

Microhardness

CONCLUSIONSThe following conclusions may be drawn from this research:

In the as cast Condition

• Addition of Mo, Ti, or Ti+B to ZA22 resulted in grain refinement of its structure. The best refining was obtained by addition of 0.05% Ti-0.01% B followed by 0.15%Ti and finally Mo at a rate of 0.1%.

• Addition of Ti, or Ti+B to ZA22 resulted in increasing its mechanical strength whereas; addition of 0.1% Mo resulted in decreasing its mechanical strength. The best enhancement in the mechanical strength of the ZA22 alloy was achieved by addition of 0.15% Ti.

• Addition of Mo, Ti, or Ti+B to ZA22 resulted in decrease of its micro hardness. The maximum decrease in the microhardness of ZA22 alloy was at the addition of 0.15%Ti, followed by 0.05% Ti-0.01% B. B. After Pressing by ECAP

• Applying ECAP process to ZA22, ZA22-0.15% Ti, and ZA22-0.1% Mo, resulted in further refining their structure, whereas applying the ECAP process to ZA22-0.05% Ti-0.01% B resulted in coarsening its structure.

• Applying ECAP process to ZA22 and its micro alloys resulted in decreasing their mechanical strengths and their micro hardness.

Thank you for your Attention