Physical Metallurgy and processing of

Intermetallic Compounds

Physical Metallurgy and processing of

Intertnetallic Contpounds

Edited by N. S. Stoloff

Rensselaer Polytechnic Institute

v. K. Sikka Oak Ridge National Laboratory

CHAPMAN & HALL

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1 2 3 4 5 6 7 8 9 10 XXX 01 00 99 98 97 96

Library of Congress Cataloging-in-Publication Data

Physical metallurgy and processing of intermettalic compounds / [edited by] Norman S. Stoloff and Vinod K. Sikka.

p. cm. Includes bibliographical references and indexes. ISBN-13: 978-1-4612-8515-1 e-ISBN-13: 978-1-4613-1215-4 DOl: 10.1007/978-1-4613-1215-4 1. Intermetallic compounds. II. Sikka, Vinod K.

TA483.P495 1994 669' .9-<lc20

2. Alloys. 3. Physical metallurgy. I. Stoloff, N.S.

94-18509 CIP

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Contents

Preface N. S. Stoloff and V. K Sikka

Contributors

I BASIC PROPERTIES

1 Defect Structures M. Yamaguchi and Y. Shirai

2 Grain Boundary Structure and Chemistry V. Vitek and Min Yan

3 Brittle Fracture and Toughening E. M. Schulson

4 Creep MY. Nazmy

5 Fatigue N. S. Stoloff

ix

xi

3

28

56

95

126

v

vi Contents

II BEHAVIOR OF ALLOY SYSTEMS

6 The Physical and Mechanical Metallurgy of Ni3Al and its Alloys

N. S. StoloJf and C. T. Liu

7 The Physical and Mechanical Metallurgy of NiAl R. D. Noebe, R. R. Bowman, and M V. Nathal

8 Titanium Aluminides F. H. Froes and C. Suryanarayana

9 Iron Aluminides C. G. McKamey

10 Advanced Intermetallics K S. Kumar

11 Silicides M. 1. Maloney and D. Shah

III ENVIRONMENTAL EFFECTS

12 Environmental Embrittlement N. S. StoloJf

13 Aqueous Corrosion R. A. Buchanan, J. G. Kim, R. E. Ricker, and L. A. Heldt

IV PROCESSING

14 Processing of Aluminides V. K Sikka

159

212

297

351

392

441

479

517

561

Contents vii

15 Powder Metallurgy Processing 605 R M. German and R G. Iacocca

16 Joining 655 S. A. David and M. L. Santella

Index 677

Preface

The attractive physical and mechanical properties of ordered intermetallic alloys have been recognized since early in this century. However, periodic attempts to develop intermetallics for structural applications were unsuc­cessful, due in major part to the twin handicaps of inadequate low-temper­ature ductility or toughness, together with poor elevated-temperature creep strength. The discovery, in 1979, by Aoki and Izumi in Japan that small additions of boron caused a dramatic improvement in the ductility of Ni3Al was a major factor in launching a new wave of fundamental and applied research on intermetallics. Another important factor was the issuance in 1984 of a National Materials Advisory Board reported entitled "Structural Uses for Ductile Ordered Alloys," which identified numerous potential defense-related applications and proposed the launching of a coordinated development program to gather engineering property and processing data. A substantial research effort on titanium aluminides was already underway at the Air Force Materials Laboratory at Wright­Patterson Air Force Base in Ohio and, with Air Force support, at several industrial and university laboratories. Smaller programs also were under­way at Oak Ridge National Laboratory, under Department of Energy sponsorship. These research efforts were soon augmented in the United States by funding from Department of Defense agencies such as Office of Naval Research and Air Force Office of Scientific Research, and by the National Science Foundation. Increased research support from several

ix

x Preface

branches of the Department of Energy was funneled to both National Laboratories (Oak Ridge and Los Alamos), as well as to many universities. Research efforts also expanded rapidly in Japan, France, Germany, and later in China. Particularly noteworthy was the launching of a Japanese National Project on Intermetallics, funded by Ministry of International Trade and Industry and by industry, with TiAl and Nb3Al as the focus of a coordinated effort to develop new high temperature alloys.

As a result of this remarkable increase in activity in the field of intermetallics, numerous conferences, workshops, and symposia on inter­metallics were held throughout the world, starting with a biannual sympo­sium on High Temperature Ordered Intermetallic Alloys, held at the Materials Research Society Fall Meeting of 1984. As of the end of 1994, at least eighteen general conference proceedings were in print in English, and others were in preparation.

The editors were approached in 1991 by several publishers to pre­pare a book on Structural Intermetallics. Because of the explosion in information generated on intermetallics during the last decade, we de­cided to enlist the aid of experts in a wide variety of fields to help us to carry out this project. We are grateful for their contributions. In planning the scope of the book we took the point of view that no matter how attractive some intermetallics appear to be in the laboratory, the key to successful utilization of these new materials resides in the effective use of modem processing techniques to provide desired microstructures and properties. Accordingly, we have included chapters on powder as well as on melt processing, and other chapters include additional information on processing. Another key feature of this book is its emphasis on aluminides and silicides. These are the classes of intermetallics that have been most intensively studied, and, therefore, are most likely to be successfully applied in commerce. Chapters on creep, fatigue, and fracture also are highlighted in this book because these are the areas where improvement in properties of intermetallics was most clearly needed. One factor that was unrecognized until very recently is the major impact that moisture and hydrogen have on low-temperature fracture behavior of many inter­metallics. Therefore, a separate chapter entitled 'Environmental Embrit­dement' is devoted to this issue.

It is hoped that this book, with its emphasis on alloy development, processing, mechanical properties, and structural applications will prove to be a basic reference source as well as a valuable adjunct to the conference proceedings mentioned earlier.

N. S. Stoloff v. K. Sikka

Contributors

Dr. R. R. Bowman NASA Lewis Research Center Mail Stop 49-3 21000 Brookpark Rd. Cleveland, OH 44135

Dr. Ray A. Buchanan University of Tennessee 434 Dougherty Engineering

Building Knoxville, TN 37996-2200

Dr. S. A. David Oak Ridge National Laboratory P.O. Box 2008 Oak Ridge, TN 37831-6095

Professor F. H. Froes Institute for Materials and

Advanced Processes University of Idaho Moscow, ID 83843

Professor Randall German Engineering Science and

Mechanical Engineering Dept. Penn State University 227 Hammond Building University Park, PA 16802

Professor L. A. Heldt Department pf Metallurgical and

Materials Engineering Michigan Technological University Houghton, MI 49931-1295

Dr. Ronald G. Iacocca Engineering Science and

Mechanical Engineering Dept. Penn State University 227 Hammond Building University Park, PA 16802

xi

xii Contributors

Dr. J. G. Kim University of Tennessee 434 Dougherty Engineering

Building Knoxville, TN 37996-2200

Dr. K. S. Kumar Martin Marietta Laboratories 1450 South Rolling Road Baltimore, MD 21227-3898

Dr. C. T. Liu Oak Ridge National Laboratory P. O. Box 2008 Oak Ridge, TN 37831-6114

Dr. M. J. Maloney Pratt & Whitney Aircraft P. O. Box 109600 West Palm Beach, FL 33410-9600

Dr. C. McKamey Oak Ridge National Laboratory P. O. Box 2008 Oak Ridge, TN 37831-6114

Dr. M. V. Nathal NASA Lewis Research Center Mail Stop 49-3 21000 Brookpark Rd. Cleveland, OH 44135

Dr. M. Nazmy Senior Scientist and Group Leader ABB Power Generation Ltd. 5401 Baden Switzerland

Ronald D. Noebe NASA Lewis Research Center Mail Stop 49-3 21000 Brookpark Rd. Cleveland, OH 44135

Dr. Richard E. Ricker Corrosion & Wear Group Metallurgy Division National Institute of Standards and

Technology Clopper Road Gaithersburg, MD 20899

Dr. M. L. Santella Oak Ridge National Laboratory P. O. Box 2008 Oak Ridge, TN 37831-6115

Professor Erland Schul son Dartmouth College Thayer School of Engineering Tuck Drive Hanover, NH 03755

Dr. Dilip Shah Pratt and Whitney Acraft East Hartford, CT 06108

Dr. Yasuharu Shirai Kyoto University Department of Metal Science and

Technology Sakyo-Ku Kyoto 606 Japan

Dr. V. K. Sikka Oak Ridge National Laboratory Metalworking Theory and Practice Metals and Ceramics Division P. O. Box 2008 Oak Ridge, TN 37831

Professor N. S. Stoloff Materials Engineering Department Rensselaer Polytechnic Institute Troy, NY 12180-3590

Dr. C. Suryanarayana Institute for Materials and

}\dvanced Processes University of Idaho Moscow, 10 83843

Professor Vaclav Vitek University of Pennsylvania Department of Materials Science

and Engineering 3231 Walnut 201 LRSM Philadelphia, P}\ 19104-6272

Contributors xiii

Professor Masahara Yamaguchi Kyoto University Department of Metal Science and

Technology Sakyo-Ku Kyoto 606 Japan

Dr. M. Yan University of Pennsylvania Department of Materils Science and

Engineering 3231 Walnut 201 LRSM Philadelphia, P}\ 19104-6272

Physical Metallurgy and processing of

Intermetallic Compounds