Chemistry and Physics of Fracture PDF
Preview Chemistry and Physics of Fracture
Chemistry and Physics of Fracture NATO ASI Series Advanced Science Institutes Series A series presenting the results of activities sponsored by the NA TO Science Committee, which aims at the dissemination of advanced scientific and technological knowledge, with a view to strengthening links between scientific communities. The series is published by an international board of publishers in conjunction with the NATO Scientific Affairs Division A Life Sciences Plenum Publishing Corporation B Physics London and New York C Mathematical D. Reidel Publishing Company and Physical Sciences Dordrecht, Boston, Lancaster and Tokyo D Behavioural and Social Sciences Martinus Nijhoff Publishers E Applied Sciences Dordrecht, Boston, Lancaster F Computer and Systems Sciences Springer Verlag G Ecological Sciences Berlin, Heidelberg, New York, London, H Cell Biology Paris, and Tokyo Series E: Applied Sciences - No. 130 Chemistry and Physics of Fracture edited by R.M. Latanision Massachusetts Institute of Technology Cambridge, MA, USA and R.H. Jones Battelle Northwest Laboratories Richland, WA, USA 1987 Martinus Nijhoff Publishers ... 1111 Dordrecht I Boston I Lancaster Published in cooperation with NATO Scientific Affairs Division .~ Proceedings of the NATO Advanced Research Workshop on "Chemistry and Physics of Fracture", Bad Aeichenhall, FAG, June 23-July " 1986 NATO AdYlnced &eaelrch Worklho~ on ~Che.lltry Ind Phyl1u of Fractur"~ (1986 : BId &e1chenblll, Ger_lIr) Che_lttr,. and ph,..lu of fuctun. (NATO ASl .ertu. Seriu E, AppUed .e1ellcu 110. 130) ~Proeeedi~s of the IIATO Adv.nced &elesrch Workshop 011 'Cheatstry .nd Phy.le. of Fr.cture,' BId &etchenball, FRC, June 2)-July I, 1986"--T.p. ver.o. Includes biblioar'phiel Ind lnde •. I. Fracture aechanics--Conare ••e l. 2. Corrollon and Intl-corro.lvel--tongrelae,. J. Stre •• corrolion- Co~re ..u . 1. Lltillillon, 1. M. 11. Jonn , 1. H. III. North Atlantic Tre.ty Ora.ni •• tlon. ScIentIfic Affl1n DhiliOll. lV. Title. V. Sertn . TA409.N4 1986 620.1'122 81-1S41S ISBN· I): 918-94-010-8140-5 c·ISBN·IJ: 918-94-009-3665-2 001: 10.10011918-94-009-3665-2 Cistributors lor the United States and Canada: Kluwer Academic Publishers, P.O. Box 358, Accord Station, Hingham, MA 02018.0358, USA Distribulors for the UK and Ireland: Kluwer Academic Publishers, MTP Press lid, Falcon House, Queen Square, lancaster LA1 1RN, UK Distributors for all other countries: Kluwer Academic Publishers Group, Distribution Center, P.O. Box 322, 3300 AH Oordrecht, The Netherlands 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, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publishers, Martinus Nijhoff Publishers, P.O. Box 163, 3300 AD Oordrecht, The Netherlands. Copyright © 1987 by Martinus Nijhoff Publishers, Dordrecht. Softcover reprint of the hardcover I sle dition 1987 v Preface For many years it has been recognized that engineering materials that are-tough and ductile can be rendered susceptible to premature fracture through their reaction with the environment. Over 100 years ago, Reynolds associated hydrogen with detrimental effects on the ductility of iron. The "season cracking" of brass has been a known problem for dec ades, but the mechanisms for this stress-corrosion process are only today being elucidated. In more recent times, the mechanical properties of most engineering materials have been shown to be adversely affected by hydrogen embrittlement or stress-corrosion cracking. Early studies of environmental effects on crack growth attempted to identify a unified theory to explain the crack growth behavior of groups of materials in a variety of environments. It is currently understood that there are numerous stress-corrosion processes some of which may be common to several materials, but that the crack growth behavior of a given material is dependent on microstructure, microchemistry, mechanics, surface chemistry, and solution chemistry. Although the mechanism by which various chemical species in the environment may cause cracks to propagate in some materials but not in others is very complex, the net result of all environmentally induced fracture is the reduction in the force and energy associated with the tensile or shear separation of atoms at the crack tip. Herein lies both the simplicity and complexity of the atomistics of crack tip processes: while it is possible to analyze the energetics of the separation of atom pairs or small groups of atoms, experimental crack growth measurements cannot presently be made at the atomic level and therefore involve the tensile and/or shear separation of millions of atoms. Furthermore, the interaction of the crack with complex microstructural features such as dislocations, dispersed phases, solute atoms, interfaces and free sur faces contributes to the nature of crack growth as a collective phenom enonand can be a major factor controlling crack propagation in a given material-environment combination. The way' in which chemical species in the environment interact can also complicate the atomistics of crack growth processes. For example, whether a species such as hydrogen influ ences crack growth by its adsorption and concentration on the crack tip surface or by its presence within the material ahead of the crack remains an open issue today. Nonetheless, the atomistics of fracture can be divided into unit processes that deal with the chemistry, mechanics, and microstructural aspects of fracture. For instance, identifying the differences in the chemical, physical, or mechanical states between propagating and non propagating cracks can yield considerable information about the critical conditions for crack growth. Likewise, the kinetics of fracture proces ses can be studied by rate theory, with the rate-determining step describing the critical mechanism in crack propagation. To provide a forum for international and interdisciplinary discussion on this complex and controversial subject, the Advanced Research Workshop on Chemistry and Physics of Fracture was held from 23 June through 1 July 1986 at the Hotel Axelmannstein in Bad Reichenhall, FRG. Sixty delegates from fifteen countries were in attendance, representing a wide range of VI disciplines and research interests: metallurgy, solid-state and solution chemistry, physics, fracture mechanics, surface science and electrochem istry. The conference format and organization followed that used suc cessfully in two previous NATO workshops on similar topics, the Advanced Study Institute on Surface Effects in Crystal Plasticity, 1975, and the Advanced Research Institute on Atomistics of Fracture, 1981. The first four days were devoted to introductory and overview lectures on theory of fracture, solid-state chemistry and physics of fracture, solution chemis try, and structure and properties of interfaces. After a one-day break, three days of workshop sessions and a summary lecture were held. Work shop topics included novel aspects of fracture, intergranular embrittle ment, hydrogen embrittlement, and stress corrosion and corrosion fatigue. Each workshop session began with a survey lecture, which was followed by short contributed papers. Afterwards, the delegates were divided into four independent working groups to address (1) key issues within topics that were selected from a list developed by the workshop organizers, or (2) issues raised by the group. Edited summaries of the deliberations of these groups were prepared by the session chairmen and are published in the proceedings as workshop summaries. There was ample time for discussion following each lecture, and the discussions became livelier with each session. It was often necessary for the chairman to cut off discussion, as the number of questions far exceeded the time available to deal with them. Discussion continued during breaks and meals, a genuine proof of the interest and enthusiasm of the delegates. Much more than at past gatherings, individuals from various disciplines were noticeably willing to listen and talk to one another -- this alone would have made the workshop a pleasure and suc cess. While the sessions were occasionally long and arduous, there was time to relax and enjoy the scenery in the Bavarian Alps around Bad Reichenhall. Breaks in the sessions were alternated between morning, afternoon and evening. Activities included sightseeing in Salzburg, Austria; a unique visit to the salt mine in Bad Reichenhall; an oppor tunity to hear the Bartok-Quartett from Budapest; a day-long tour to the Konigsee and Berchtesgaden and other interesting places. The photographs included in this volume are certain to remind the delegates of both the technical sessions and the beautiful surroundings of the workshop. Many thanks are due to members of the organizing committee for their help in developing and conducting this workshop and to the delegates for their significant contributions to the success of the workshop. This workshop was organized under the aegis of the Double Jump Programme of the NATO Scientific Affairs Division with the aim of promoting closer international cooperation between universities and industries on the projects of industrial interest. We are, therefore, grateful to NATO and to our Double Jump partners and to the U.S. Army Research Office for providing the financial resources without which this workshop could not have been held. We believe that industry will find that the new, first principle understanding that is emerging may well lead to improved performance in the case of contemporary materials and, ultimately, to the evolution of new engineering materials designed from the molecular stage to resist embrittlement. Advanced technologies of all kinds demand ~I industrial materials capable of performing in increasingly more hostile circumstances. This workshop and the spirit of international cooperation that it has stimulated will, we believe, serve as a guide in meeting technology's challenges. Finally, we acknowledge with great pleasure the superb assistance of Lisa Kaminski and Christa Parsons, who handled logistical problems and large volumes of typing during the course of the workshop, and Pam Whiting, Marji Cochran, and Connie Beal, who assisted in the prepara tion of the Proceedings. December 1986. R.M. Latanision R.H. Jones VIII ORGANIZATION Chairmen: R. M. Latanision Massachusetts Institute of Technology, U.S.A. R. H. Jones Battelle Northwest Laboratories, U.S.A. Organizing COll1llittee: M. Daw, Sandia National Laboratory, Livermore, CA, U.S.A. D. J. Duquette, Rensselaer Polytechnic Institute, Troy, NY, U.S.A. M. E. Eberhart, Los Alamos National Laboratory, Los Alamos, NM, U.S.A. T. E. Fischer, Exxon Research &E ngineering Co., Annandale, NJ, U.S.A. G. S. Frankel, IBM Watson Research Center, Yorktown Heights, NY, U.S.A. J. P. Hirth, Ohio State University, Columbus, OH, U.S.A. R. H. Jones, Battelle Northwest Laboratories, Richland, WA, U.S.A. J. F. Knott,Cambridge University, Cambridge, England, U.K. R. M. Latanision, Massachusetts Institute of Technology, Cambridge, MA, U.S.A. • P. Neumann, Max-Planck-Institut fur Eisenforschung, Dusseldorf, FRG J. R. Rice, Harvard University, Cambridge, MA, U.S.A. A. W. Thompson, Carnegie-Mellon University, Pittsburg, PA, U.S.A. R. Thomson, National Bureau of Standards, Gaithersburg, MD, U.S.A. G. Whitesides, Harvard University, Cambridge, MA, U.S.A. Sponsors: North Atlantic Treaty Organization U.S. Army Research Office Battelle Northwest Laboratories Cabot Corporation Martin-Marietta Corporation Rockwell International Shell Oil Company IX Contents INTRODUCTORY LECTURES A. S. Argon Chemistry and Physics of Fracture: An Overview 3 G. M. Whitesides and T. X. Neenan What. If Anything. Can Chemistry Offer to Fracture Mechanics? 12 J. R. Rice Mechanics of Brittle Cracking of Crystal Lattices and Interfaces. 23 J. F. Knott Materials Science of Fracture Processes. 44 THEORY OF FRACTURE P. Neumann Plastic Processes at Crack Tips. 63 P. Neumann and H. Vehoff Discussion: Remark Concernin0. the Evidence of Cleavage in Our Experiments in Single Crystals of Fe2.6%Si. 85 R. M. McMeeking Plastic Flow Instabilities at Crack Tips. 91 A. W. Thompson Distributed Damage Processes in Fracture. 129 J. W. Hancock A Comparison of Void Growth and Ductile Failure in Plane and Axisymmetric States of Strain. 148 SOLID STATE CHEMISTRY AND PHYSICS OF FRACTURE M. E. Eberhart and D. D. Vvedensky Theoretical Approaches to Materials Design: Intergranular Embrittlement. 163 x M. W. Finnis Interatomic Forces and the Simulation of Cracks. 177 M. S. Daw and M. I. Baskes Application of the Embedded Atom Method to Hydrogen Embrittlement. 196 K. Sieradzki Theory of Environmental Effects on Transgranular Fracture. 219 SOLUTION CHEMISTRY D. D. Macdonald Surface Chemistry in Aqueous Solutions. 255 A. Turnbull Crack-Tip Electrochemistry: Recent Developments. 287 M. Pourbaix Electrochemical Thermodynamics and Kinetics and Their Application to the Study of Stress- Corrosion Cracking. 311 STRUCTURE AND PROPERTIES OF INTERFACES J. R. Smith, J. Ferrante, P. Vinet, J. G. Gay, R. Richter and J. H. Rose. Universal Properties of Bonding at Metal Interfaces. 329 J. Th. M. De Hosson and V. Vitek Structure of Grain Boundaries and Interfaces. 363 H. J. Grabke Segregation at Interfaces. 388 WORKSHOP SESSIONS Workshop Session 1: Novel Aspects of Fracture W. W. Gerberich Novel Techniques as Applied to Fracture Process Zone Theory. 419 Short Presentations C. G. Park and S. M. Ohr In Situ TEM Studies of Crack Tip Deformation in Molybdenum. 437
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