MATERIALS SCIENCE RESEARCH. Volume 1

Transcription

1 MATERIALS SCIENCE RESEARCH Volume 1

2 MATERIALS SCIENCE RESEARCH Volume 1 The Proceedings of the Research Conference on Structure and Properties of Engineerin~ Materials, held March 12-13, 1962, at North Carolina State College, Raleigh, N. C. Conducted by the School of Engineering and the College Extension Division of North Carolina State College in cooperation with the U. S. Army Research Office (Durham) Edited by H. H. Stadelmaier and W. W. Austin SPRINGER SCIENCE+BUSINESS MEDIA, LLC 1963

3 Library of Congress Catalog Card Number Springer Science+Business Media New York Originally published by Consultants Bureau Enterprises, Inc. in 1963 Softcover reprint of the hardcover 1st edition 1963 ISBN ISBN (ebook) DOI /

4 FOREWORD The synthesis of the properties of an aggregate structure from a knowledge of the behavior of the individual particles is a task of no mean proportions. Attacks on this problern have not been lacking, but the greater emphasis in materials research has always been on the more attractive studies of crystals or the continuum. Most of the materials used by man are in the aggregate state and therefore the group that organized this conference feit an urgent need for a review of our present state of knowledge about aggregate materials in their relation to their particulate building blocks. Papers have been contributed from the entire materials field including metals, inorganic nonmetals, and plastics. There is a strong emphasis on dislocations and mechanical properties, an outgrowth of the practical demand for materials capable of withstanding extreme forces and temperatures. The technical content of the conference is reflected in the four sections of the book, I. Bridging the Gap Between Particulate Concepts and Properties of Materials, II. Structure and lmperfections, III. Aggregate Structures, IV. Continuum Properties. They combine interpretive papers by outstanding representatives of their field with papers that report the results of recent research work. In Part I we are first introduced to the subject of polymer plastics and shown how the mechanical pröperties are related to the macromolecular structure. This is followed by an authoritative account of the rationalization of plastic behavior based on the mechanisms of single-crystal deformation. A relative latecomer among physical properdes is ferroelectricity, discussed in the third paper. Part II focuses on imperfections. First, the grain boundary itself is reviewed as it affects sintering and creep. There follow detailed accounts of defects in silver chloride and dislocations in spinels and related structures. Dislocation multiplication is reviewed in an account that is supported by recent electron microscopic observations. Surface imperfections have a striking effect on the mechanical strength of brittle materials. The paper on this subject can be said to deal with an unusual aggregate structure: the crystal and its surface coating. Part III is concerned with more conventional aggregate structures. There are two reports on polycrystalline ceramics, one discusses the dislocation-grain boundary interaction leading to embrittlement in ionic materials, the other plastic deformation in polycrystalline spinel. Polycrystalline meta! films are the subject of a paper on thin films of tantalum, and aggregates containing precipitated phases are discussed in a report on quench-aging and strain-aging in iron and steel. Part IV deals with the continuum. The first paper reviews the recent develop- V

5 VI Foreword ments in theories of the stress-strain behavior of materials subjected to various environments. It is followed by a paper showing how dislocations may be introduced into continuum mechanics. New experimental methods of exploring statistical fracture theories are described in a paper on the strength of polycrystalline alumina. The final paper surveys the significant dynamic properties for the characterization of polymer plastics and shows which new methods are being adopted to test them. The Research Conference on the Structure and Properties of Engineering Materials was held in Raleigh, North Carolina on March 12 and 13, 1962, under the jointsponsorship of the School of Engineering and the College Extension Division of North Carolina State College and the U. S. Army Research Office (Durham), and it is a pleasure to acknowledge the efforts of the many individuals of these organizations who contributed to the success of the conference. The assistance of Mrs. I. Koopmann-Simonsen and Mr. G. Hofer with the proofreading and indexing is gratefully acknowledged. The Editors

6 COMMITTEE PERSONNEL General Chairman N. W. Conner, N. C. State College Program W. W. Austin, P. H. McDonald, Hayne Palmour III, H. H. Stadelmaier, R. F. Stoops, N. C. State College; F. K. Weddeling, U. S. Army Research Office (Durham); Ralph Evans, Research Triangle Institute Arrangements G. L. Goglia, D. B. Stansel, H. A. Lamonds, Hayne Palmour 111, N. C. State College; J. B. Shea, Research Triangle Park Publicity W. W. Kriege!, Mary Yionoulis, N. C. State College Transportalion K. R. Brose, S. W. Derbyshire, W. C. Hackler, N. C. State College; J. B. Shea, Research Triangle Park Social E. M. Schoenborn, R. A. Douglas, N. C. State College; Ralph Evans, Research Triangle Institute Keynote Speaker E. Orowan, Massachusetts Institute of Technolorzy (The keynote address, "Bridging the Gap/' was not available for publication.) Sessions Chairmen B. F. Brown, U. S. Naval Research Laboratory; R. F. Stoops, N. C. State College; F. K. Weddeling, U. S. Army Research Office (Durham); P. H. McDonald, N. C. State College Toastmaster J. H. Lampe, N. C. State College Dinner Speaker Brig. Gen. Chester W. Clark, U. S. Army VII

7 CONTENTS Part I Bridging the Gap Between Particulate Concepts and Properties of Materials Molecular Order and Mechanical Properdes of Polymer Plastics by Anton Peterlin.... On the Plastic Behavior of J:>olycrystalline Aggregates by John E. Dorn and Jim D. Mote Relation Between Electrical Properties and Microstructure of Barium Titanate by H. H. Stadelmaier and S. W. Derbyshire Part II Structure and Imperfections Grain Boundary Effects in Ceramies by J. E. Burke Point Defects and Dislocations in Silver Chloride by M. N. Kahler, H. Layer, M. G. Miller, and L. Slifkin Dislocations in Spineis and Related Structures by J. Hornstra Dislocation Multiplication by Jack Washburn The Surface-Sensitive Mechanical Behavior of Ionic Crystals by A. R. C. Westwood Part 111 Aggregate Structures Dislocations and the Strength of Polycrystalline Ceramies by R. J. Stokes and C. H. Li Deformation in Hot-Pressed Polycrystalline Spinel by Hayne Palmour III, Dong M. Choi, L. D. Barnes, R. D. McBrayer, and W. W. Kriegel Some Characteristics of Tantalum Films by M. S. P. Lucas Recent Observations on Quench-Aging and Strain-Aging of Iron and Steel by A. S. Keh and W. C. Leslie IX

8 X Contents Part IV Continuum Properties Mechanical Properties of Engineering Materials: Macroscopic Behavior by Joseph Marin The Dislocation as a Fundamental New Concept in Continuum Mechanics by Ekkehart Krön er Factors Affecting the Statistical Strengthof Alumina by N. A. Weil, S. A. Bortz, and R. F. Firestone Some Trends in the Mechanical Characterizations of Polymers by C. W. Richards Index