Other Pergamon Titles of Interest ASHBY & FROST Perspectives in Creep Fracture ASHWORTH Ion Implantation into Metals BARRETT & MASSALSKI Structure of Metals, 3rd Edition EL GUINDY Precious Metals 1982 FROST & ASHBY Deformation-Mechanism Maps GIFKINS Strength of Metals and Alloys (3 Volume Set) HARRIS Mechanical Working of Metals JOHNSON Plane Strain Slip Line Fields for Metal Deformation Processes MANN Bibliography on the Fatigue of Materials, Components & Structures, Volume 3, 1961-1965 MILLER Mechanical Behaviour of Materials (3 Volume Set) NIKU LARI Shot Peening OSGOOD Fatigue Design, 2nd Edition SIH Progress in Fracture Mechanics Pergamon Journals of Related Interest Free Specimen Copy Sent on Request Acta Metallurgica Canadian Metallurgical Quarterly Corrosion Science Engineering Fracture Mechanics Fatigue of Engineering Materials & Structures International Journal of Solids & Structures Journal of the Mechanics & Physics of Solids Materials Research Bulletin Metals Forum Scripta Metallurgica The Physics of Metals & Metallography Specialty Steels and Hard Materials Proceedings of the International Conference on Recent Developments in Specialty Steels and Hard Materials (Materials Development '82) held in Pretoria, South Africa, 8-12 November 1982 Edited by N. R. COMINS and J. B. CLARK Council for Scientific & Industrial Research, Pretoria, South Africa PERGAMON PRESS OXFORD NEW YORK TORONTO SYDNEY PARIS FRANKFURT U.K. Pergamon Press Ltd., Headington Hill Hall, Oxford OX3 OBW, England U.S.A. Pergamon Press Inc., Maxwell House, Fairview Park, Elmsford, New York 10523, U.S.A. CANADA Pergamon Press Canada Ltd., Suite 104, 150 Consumers Road, Willowdale, Ontario M2J 1P9, Canada AUSTRALIA Pergamon Press (Aust.) Pty. Ltd., P.O. Box 544, Potts Point, N.S.W. 2011, Australia FRANCE Pergamon Press SARL, 24 rue des Ecoles, 75240 Paris, Cedex 05, France FEDERAL REPUBLIC Pergamon Press GmbH, Hammerweg 6, OF GERMANY D-6242 Kronberg-Taunus, Federal Republic of Germany Copyright © 1983 Pergamon Press Ltd. All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means: electronic, electrostatic, magnetic tape, mechanical, photocopying, recording or otherwise, without permission in writing from the publishers. First edition 1983 Library of Congress Cataloging in Publication Data International Conference on Recent Developments in Specialty Steels and Hard Materials (1982: Pretoria, South Africa) Specialty steels & hard materials. Includes index. 1. Steel —Congresses. 2. Heat resistant materials — Congresses. I. Comins, N. R. II. Clark, J. B. III. Title. TA472.I57 1982 620.1'7 83-2410 British Library Cataloguing in Publication Data International Conference on Recent Developments in Specialty Steels and Hard Materials (1982 Pretoria) Specialty steels & hard materials. 1. Steel —Congresses I. Title II. Comins, N.R. III. Clark, J.B. 669'.142 TN730 ISBN 0-08-029358-1 In order to make this volume available as economically and as rapidly as possible the authors' typescripts have been reproduced in their original forms. This method unfortunately has its typographical limitations but it is hoped that they in no way distract the reader. Printed in Great Britain by A. Wheaton & Co. Ltd., Exeter Preface Materials Development '82 took place from 8-12 November 1982 in Pretoria, South Africa. This International Conference provided a forum for scientists, engineers and technologists to discuss recent research and development in the fields of specialty steels and hard metals. The Conference was held under the auspices of IUPAP (International Union of Pure and Applied Physics) and the high pressure section was under the sponsorship of AIRAPT (Internat- ional Association for the Advancement of High Pressure Science and Tech- nology) . South Africa is well known internationally as a major exporter of many important raw materials including chromium, vanadium, manganese, etc., some of which, such as chromium, are now regarded as strategic in many countries. There has been continuing development over the years to market these materials in ever more processed forms, and attention is now focussed on the next step in the 'Materials Life Cycle', viz., engineering materials, including novel ones particularly suited to local production. This confer- ence was the first International meeting of its kind in South Africa and was particularly valuable in illustrating the importance of Materials Science and Engineering. The meeting was attended by some 270 delegates including visitors from Germany, Israel, Japan, Republic of China, Sweden, Switzerland, U.K., U.S.A., Zambia and Zimbabwe. The programme included thirteen invited plenary lectures and thirty-six contributed research papers, all presented orally. The keynote lecturers were invited by the Organising Committee with the idea of surveying a range of aspects in each topic. The focus was on structure-property relationships with the intention of strengthening the link between the understanding of microstructural detail, alloy design, processing technology and applications, as well as including aspects of economic viability. Presentations on spec- ialty steels included discussion of high-strength low alloy steels, stain- less steels, maraging steels, high speed steels and rapid solidification processing as well as consideration of the roles of specific alloying elements. An equally wide variety of topics was to be found in the hard materials section with papers covering tungsten carbide-cobalt hard metals, non-oxide ceramics, CVD processed hard materials and coatings, synthesis of diamonds and sintered polycrystal1ine ultra-hard materials. ν vi Preface These proceedings are divided into the following categories : plenary papers covering the entire range of materials of interest in the conference, con- tributed specialty steel papers and contributed hard materials papers. Contributed papers were selected by the Programme Committee and refereed as complete but draft manuscripts before the final versions were prepared. It is hoped that this volume will provide timely reviews as well as significant research and development contributions in the field of specialty steels and hard materials. Ν.R.Comins J.B.Clark Pretoria, South Africa. Acknowledgements The sponsorship of the following organisations is gratefully acknowledged: Boart International Limited Council for Mineral Technology (MINTEK) Council for Scientific and Industrial Research (CSIR) Co-operative Scientific Programmes (CSPj National Physical Research Laboratory (NRPL) De Beers Industrial Diamond Division (Pty) Ltd (DEBID) Highveld Steel and Vanadium Corp Ltd ISCOR Ltd Middelburg Steel and Alloys (Pty) Ltd Nuclear Development Corporation of South Africa (Pty) Ltd Sandvik (Pty) Ltd SCAW Metals Ltd Steel and Engineering Industries Federation of SA (SEIFSA) South African Coal Oil and Gas Corp Ltd (SASOL) Union Steel Corp of SA (USCO) Appreciation is also due to: Avis Rent-a-Car South African Institute of Chemistry South African Institute of Physics South African Powder Metallurgy Association South African Tourist Corp (SATOUR) South African Transport Services Technical Services Department, CSIR The Southern Africa Stainless Steel Development Association (SASSDA) and the following hosts for technical visits during the Conference: Boart Hardmetals (Pty) Ltd Chamber of Mines of South Africa Council for Mineral Technology De Beers Industrial Diamond Division (Pty) Ltd Highveld Steel and Vanadium Corp Ltd ISCOR Ltd viii Acknowledgements Union Steel Corp of SA The Organizers also wish to thank those organizations which supported the Conference by way of purchasing advertising or exhibition space or by send- ing delegates. Thanks are due particularly to the members of the various Conference Commit- tees, and above all to the Organizing Committee and Conference Secretariat. For Mrs Cilia Taylor, who ran the Secretariat and was responsible for the conference arrangements and much of the co-ordination, a special vote of thanks. The smooth running and friendly and stimulating atmosphere achieved at this meeting is a tribute to the efforts of all these people. Organizing Committee Dr J Β Clark (Chairman) National Physical Research Laboratory, CSIR Mr R Ρ Badenhorst ISCOR Ltd Mrs Ν Basson National Physical Research Laboratory, CSIR Dr J V Bee University of the Witwatersrand Dr Ν R Comins National Physical Research Laboratory, CSIR Mr Κ Dresselhaus Union Steel Corp of SA Ltd Prof G G Garrett University of the Witwatersrand Mr R A Pacey Co-operative Scientific Programmes, CSIR Mr Β Ε Protheroe Chamber of Mines of SA Dr G J Rees Boart International Ltd Mrs Ρ M Taylor Symposium Secretariat, CSIR Dr C R Thomas Middelburg Steel & Alloys (Pty) Ltd Dr Ρ Τ Wedepohl Council for Mineral Technology Dr R J Wedlake De Beers Industrial Diamond Division (Pty) Ltd National Advisory Committee Dr J Β Clark (Chairman) National Physical Research Laboratory, CSIR Dr L Alberts Council for Minerai Technology Dr Η Β Dyer De Beers Industrial Diamond Division (Pty) Ltd Dr W Güldenpfennig Union Steel Corp of SA Ltd Mr Hall Highveld Steel & Vanadium Corp Ltd Mr C Hall Middelburg Steel & Alloys (Pty) Ltd Dr Β Luyckx University of the Witwatersrand Prof F R Ν Nabarro University of the Witwatersrand Mr J M Pretorius Nuclear Development Corporation of South Africa (Pty) Ltd Mr Κ Prince ISCOR Ltd Dr H J Smith Co-operative Scientific Programmes, CSIR Dr A Strasheim National Physical Research Laboratory, CSIR Prof G Τ van Rooyen University of Pretoria Acknowledgements ix International Advisory Committee Dr F Ρ Bundy General Electric Company, USA Prof M Cohen Massachusetts Institute of Technology, USA Dr H Ε Exner Max-Planck-Institut für Metal 1forschung, FRG Prof Dr H Fischmeister Max-Planck-Institut für Metallforschung, FRG Prof R W Κ Honeycombe University of Cambridge, UK Dr Β F Kieffer Teledyne Inc, USA Prof F R Ν Nabarro University of the Witwatersrand, RSA Dr M Semchyshen Climax Molybdenum Co, USA Prof R Ε Small man University of Birmingham, UK Prof Η Suzuki University of Tokyo, Japan Prof G Thomas University of California, Berkeley, USA Prof B-Z Weiss Technion, Israel In preparing these proceedings, the editors have benefited from the untiring help and support of many people. Mrs Sanny Biagio was responsible for the administrative work on the proceedings, and Mrs Nicolene Basson for much of the language editing of all manuscripts. Many papers required alterations and this would not have been possible without the support of Mrs Susan Stephan, Ms Maureen Taverner, Mrs Fran Obermeyer, Mrs Dottie Visser, Mrs Adele Foreman, Mrs Santie Mörsner and Mrs Irma Uytenbogaardt, who during the Conference, and after, assisted in the Editorial Office. Thanks also to Dr Martin Shaw, Mrs Janet McQueer, Miss Dorothy Park and Mrs Margaret Comins for their assistance. The authors are thanked for their co-operation throughout the refereeing procedure, for their prompt submission of manuscripts, and where this was not the case, their tolerance of the many telexes. Finally, to the many unnamed referees who ensured that the manuscripts were up to standard, and all the other people involved in making the Conference the success it was, our hearty thanks. Rapid Solidification Processing and the Control of Structure/Property Relationships M. Cohen Massachusetts Institute of Technology, Cambridge, MA 02139, USA ABSTRACT In general, materials processing plays a major role in the structure/proper- ty relationships which make materials useful to society. A recent illustra- tion of this dynamic interplay is provided by rapid solidification process- ing which leads to compositional uniformity and extremely fine dispersions of second-phase precipitates. The fundamental modes of solidification are discussed, particularly from the standpoints of solute partitioning at the solid-liquid interface, solute trapping, and massive (segregationless) solidification. Segraaationless solidification can produce unusually high degrees of super-saturation relative to phases which are otherwise difficult to dissolve in the solid matrix. This condition is favoured by supercooling of the solidification process and by high velocity of the solid-liquid in- terface. An important consequence of such rapid solidification is that the alloy chemistry can be potentially designed to create small second-phase precipitates which are particularly insoluble in the solid matrix and which therefore resist coalescence on subsequent processing at high temperatures. As a result, these dispersions are very effective in pinning grain bound- aries and inhibitinq grain growth of the matrix phase. Some recent findings are presented dealinq with the influence of these microstructural features on structure/property relationships in alloy systems. KEY WORDS Rapid solidification; solidification morpholoqy; solute partitioning; in- terfacial velocity; massive solidification; second-phase dispersions; materials processinq/structure/property relationships. INTRODUCTION Structure/property relationships in materials constitute the essence of materials science. Here, we try to discern the inner architecture of mate- rials and then to connect this microdomain (throuqh theories, models, or 1