W. T. Read. Dislocations in Crystals*). Metallurgizdat, 1957, 279 pp., price 13 rubles 20 kopecks, print run 4,000 copies.

Despite the broad use of dislocation theory in modern solid-state physics, until recently this theory had been extremely scantily covered in Soviet literature. It is therefore not surprising that readers of various specialties received with such interest the appearance in print of Read’s book, Dislocations in Crystals. Read’s book is essentially a textbook on the foundations of dislocation theory, written in a very clear and simple language. The author consistently presents the theory of dislocations as of 1953, trying to separate what is reliably known about dislocations from various hypothetical constructions that arbitrarily adapt dislocation concepts in order to “explain” any experimental facts. The author’s critical and rigorous scientific approach to dislocation theory has been positively assessed by many Soviet scholars. It is no accident that Read’s textbook is used by Yu. N. Rabotnov, V. R. Regel, and V. N. Rozhanskii in lectures for students of the mechanics-and-mathematics, physics, and chemistry faculties of Moscow State University.

The book requires of the reader only elementary knowledge in mathematics and crystallography. For all the basic propositions of the mathematical theory of dislocations the author gives simple geometrical proofs, the assimilation of which is also facilitated by clear and vivid illustrations. The exposition is accompanied by numerous problems and questions that make the reader think over the material read and understand more deeply the problems raised by the author. At the end of each chapter the reader is invited to solve several examples independently, draw diagrams illustrating the propositions set forth in the chapter, or prove mathematical theorems supplementing the chapter.

In the first part of the book the basic propositions of dislocation theory are developed systematically. Beginning with the simplest examples, the author examines all possible types of dislocations. Next, the motion of dislocations is considered and its relation to the macroscopic deformation of a specimen is established.

After calculating the forces acting on dislocations in a given stress field, and the internal stresses caused by dislocations of various types, the author analyzes the principal cases of dislocation interaction and possible geometrical schemes of dislocation multiplication.

The second part of the book is devoted to applications of dislocation theory. One chapter deals with the dislocation theory of growth and its experimental confirmations. The remaining four chapters analyze questions of the dislocation theory of grain boundaries and present experimental confirmations of the correctness of a number of theoretical calculations concerning grain-boundary energy and estimates of the mobility of boundaries of different types.

Unfortunately, in the translation the sections of the book devoted to the shortcomings of dislocation theory were abridged or omitted. In the very first lines of the book the author subjects to serious criticism the earlier state of dislocation theory, when “it became fashionable to invent a dislocation theory for almost every experimental result on plastic deformation. Finally, it became obvious that dislocations can explain not only an actual, but probably any conceived, result, and usually in several different ways.”

Read decisively dissociates himself from such “theories” and regards his book as an “introduction to dislocations” from the standpoint of a new stage in the development of the theory, characterized by “critical, consistent development of the basic theory from the initial principles and the search for decisive experimental tests of the theory.” In the abridged translation, the development of dislocation theory in these lines has been deprived of rigor and, for unclear reasons, is crowned with an appeal to experimental verification.

*) Translated by V. N. Geminov and V. S. Ivanova, edited by Corresponding Member of the Academy of Sciences of the USSR I. A. Oding.

In other sections of the book one also encounters alteration of the author’s statements on methodological questions of the theory of dislocations precisely in the spirit of that unappealable style which was subjected to serious criticism in the Soviet press. On p. 14 of the translation we read: “Dislocation theory is rather a conception from which possible existing mechanisms of atomic displacement are inferred, which in real crystals can be established only by precise experiments.” In fact the author asserts something opposite: “Dislocation theory is rather a general scheme for describing possible atomic mechanisms. Which mechanisms operate in real crystals can be determined only by decisive experiments.”

In several places (§ 1–2, § 1–3, § 1–10, etc.) Read emphasizes that only as applied to questions of crystal growth and grain boundaries is the theory of dislocations capable of making unambiguous predictions, since only in these cases is arbitrariness in postulating the arrangement of dislocations excluded. In the translation these statements of the author cannot be recognized. In a number of cases this occurred because of the omission of not only individual words, but also entire phrases. Thus, on p. 179 we read: “This is where the strength of this theory lies.” Read had: “The strength and weakness of dislocation theory,” etc. Further, the words about the ambiguous “explanations,” typical of most problems of plastic deformation, which “can easily be changed to agree with experiment,” disappeared. The end of § 1–2, “Foundations of dislocation theory,” is completely distorted. In particular, the author’s reference to the powerlessness of the theory in the absence of experimental data on the arrangement of dislocations, and to the hopelessness of attempts “to derive all results from dislocation theory,” when “the number of possible conclusions is limited only by the wit, energy, and personal tastes of the theorist,” is omitted.

On the second page of the “Introduction” Read explains in detail why he refused to cover the remarkable attempts to apply dislocation theory to the problem of plastic deformation. Owing to the inaccurate translation, the impression is created that this application of the theory is contained in the book. On p. 160 the translators write: “The present chapter sets forth Cottrell’s theory of the yield limit for single crystals, and gives the exact time law of the aging process.” It is not difficult to see, however, that in this chapter Read does not set forth a theory of the yield limit and does not cover the laws of aging.

There is no doubt that since 1953, when Read’s book was written, dislocation theory has made considerable progress. However, this gives the translators no grounds for arbitrarily and without any reservations modernizing the text of the book. Disagreement with the author could have been expressed in footnotes, in the preface, etc.

Let us give a few more examples of gross departures from the text:

DISLOCATIONS IN CRYSTALS

Author

“In this paragraph the connection of the Burgers vector with possible paths of formation (or elimination) of a dislocation is shown…”

Translation (p. 48)

“In this paragraph it is shown how, with the aid of the Burgers vector, one can mentally eliminate (or create) a dislocation…”

Author

“Figs. 1–2 apply both to a monatomic layer and to the atomic plane in the crystal as a whole.”

Translation (p. 38)

“…In the present case, in a single-layer model (of soap bubbles), the disturbances are the same as in the crystal as a whole.”

The merit of Read’s book is that the theory is presented without carrying out complicated mathematical calculations. Unfortunately, the translators have not everywhere understood the notation adopted by the author; they have confused dyadic and scalar multiplication of vectors, in a number of cases they have denoted vectors as scalars and vice versa, and on p. 54 they have simply called the unit stress tensor a “coefficient,” while on p. 85 they introduced the term “dyadic stress,” by which one should by no means understand the ordinary stress tensor. In the formulas given in problem No. 2 to Chapter 8 and No. 1 to Chapter 14, the translators retained misprints present in the original, which become obvious at the very first attempt to solve these problems.

On p. 153 we read: “In what follows, a more general case of an isotropic medium will be considered, in which the stresses depend on the orientation of the plane with respect to the Burgers vector and to the axes of the crystal.” This unreal “case,” contradicting the definition of isotropy, appeared because of another obvious misprint in the original.

The translation of a number of basic terms of dislocation theory has been poorly chosen. Instead of “edge” the translators use the term “linear” dislocation, and instead of “inclination” of the boundary—“slope.” As a result, on p. 176 such a combination appears as “straight-line linear dislocation,” and in the caption to Figs. 1–2 the word “therefore,” which explains the meaning of the term, has to be thrown out of the author’s text: “note that the dislocation is the edge of an incomplete atomic plane, therefore it is called edge.” Following the translators, the ring of the edge dislocation in Fig. 4.4 had to be called a curvilinear linear dislocation, and the block boundary shown in Fig. 11.1—a slanting symmetric boundary. Among particularly unfortunate expressions one should also mention the terms “unit of slip” (p. 13) instead of “unit displacement,” “yield area” instead of “yield limit,” “elastic deformation” (p. 18) instead of “reversible deformation,” “special plane” (p. 166) instead of “slip plane,” “scalar vector” (p. 236, etc.) instead of “magnitude of the vector,” “discreteness of deformation” (p. 154) instead of “discontinuity of displacement,” and others.

The comparatively small print run (4,000 copies) of Read’s book was sold out literally in one or two days. In our view, it is absolutely necessary to publish this book in a large edition as a textbook on the fundamentals of a theory already being used in a number of branches of science and technology. In doing so it would be desirable to correct the noted shortcomings and omissions, and to provide a full translation of the text of the abridged sections (including the very valuable text of the “Introduction,” which in the original consists of only two pages), and in the preface to give a more detailed account of the progress in dislocation theory achieved since 1953.

Such additions could further increase the value of the substantial and useful work carried out by the translators.

V. L. Indenbom