PREFACE_1964_Dislocations

Prévia do material em texto

PREFACE 
THIS book originates from a course of lectures given in 1953-1955 at the 
Ecole des Mines, Paris at the physical laboratory of Institut de Recherche 
de la Siderurgie Fran£aise at Saint-Germain-en-Laye, and the metallurgy 
section of the Centre d'Energie Atomique at Saclay. Its purpose is to 
summarize the main properties of dislocations. It is intended essentially for 
research students at University and for students of engineering schools as 
well as for research engineers. It requires only a basic knowledge of math-
ematics and elementary notions of crystallography. The main physical 
laws used are recalled in the course of the text, and an Appendix 
summarizes the main results of the theory of Classical Elasticity. 
Finally, this book does not pretend to be original in any special way: 
while some of the most debatable details are presented in the author's 
own way, the major part of what follows is found in the classical 
treatises by Read (1953) and Cottrell (1953) or in the papers referred 
to in the text. 
\j The idea of dislocations dates from the beginning of this century. But 
their study, theoretical as well as experimental, has developed mainly since 
the second world war. Their presence is now known to alter not only the 
plastic properties of crystals, but also a large number of other interesting 
properties: growth rate, electrical properties of semi-conductors, formation 
of photographic images, magnetic hardness, superconductive properties, 
etc. If the possible fields of application are still wide open, the "theory" 
of these defects might be considered as nearly completed: their main 
properties are known at least approximately, and most of their possible 
geometric configurations have been explored. 
In the first part, the general properties of dislocations will be reviewed; 
the second part is devoted to the more or less complex networks of disloca-
tions which can be formed in crystals, and to the plastic properties which 
correspond to these arrays; finally, the last part is devoted to the inter-
actions of dislocations with other crystalline defects, primarily impurity 
atoms. 
Since this book is written essentially for metallurgists, simple models 
and order of magnitude arguments have been used as often as possible. 
Also, only those points which have shown some practical application have 
been developed. Thus the beautiful mathematical studies of Nye (1953), 
Bilby et al., (1954, 1955) and Kröner (1955, 1958) on the continuous dis-
tribution of infinitesimal dislocations are not studied in detail. Conversely, 
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XV111 Preface 
processes such as fatigue, which are still only incompletely understood, 
have hardly been mentioned in spite of their practical importance. 
The new English edition of the book has set some difficult problems. 
It has been impossible to take into account all the work done during the 
six years since the French edition was written. But the author has deemed 
it essential to include the very beautiful work carried out on the direct 
observation of dislocations, by optical methods as well as by X-rays and 
electron microscopy. This is surely the major contribution of recent years, 
because it has set the detailed study of dislocations on a firm ground. It is 
also satisfying to theoreticians to note that it has confirmed most of their 
predictions. The ease with which dislocations move both in a perfect 
crystal (i.e. the "Peierls-Nabarro force") and in a workhardened material 
have also been much studied and discussed recently, although with less 
success. The corresponding sections of the book therefore have been some-
what altered. The chapter on vacancies has been enlarged, to give a better 
account of their basic properties and of quenching and irradiation experi-
ments. The analysis of the plastic properties, especially workhardening, 
has been somewhat altered. Other minor corrections have also been made, 
and the misprints of the French edition corrected as far as possible. The 
author wishes to thank Dr. Vassamillet for his great help in that connection. 
The author also wishes to stress how much this book owes to the 
teaching of Professor Sir Nevill Mott, Professors F. C. Frank and 
J. D. Eshelby. Thanks are due to Professors S. Amelinckx and J. W. 
Mitchell, and to Drs. W. C. Dash, J. J. Gilman, P. B. Hirsch, P. A. 
Jacquet, W. G. Johnston, A. R. Lang, F. L. Vogel and M. J. Whelan 
for the photographs reproduced in the text, and to many other people 
for their criticisms of the French edition, especially Professors A. H. 
Cottrell, F. C. Frank and A. Seeger, and Drs. C. Crussard, P. B. Hirsch 
and B. Jaoul. Finally the author acknowledges the permission given by 
the Philosophical Magazine, the Proceedings of the Royal Society, the 
Physical Review and the Journal of Applied Physics to reproduce some 
of their figures. 
J. FRIEDEL