Lattice defects in quenched metals

Book Redews fully only in the past ten years. The reason for the period of inactivity is traced to the lack of suitable neutron sources. The material treated in separate chapters covers neutron sources, photographic and nonphotographic detection devices. Accelerator, radioactive and reactor neutron sourcce are also described. Since thermal neutrons are used frequently, the moderating methods to obtain such neutrons are also presented. Under photographic detection methods two major ones, the direct exposure method and the so-called transfer method are well treated. I t is pointed out that the latter has the important advantage of £n~klng neutron photography also possible in the presence of strong gamma radiation. This is due to the fact that this method does not expc~ the photographic film directly to the depicting neutron radiation, but first produces a latent radioactive image by the impinging neutrons. After this exposure to neutrons, the latent radioactive picture is transferred to a photographic plate and developed by normal photographic procedures. The various screens employed in making such photographic pictures, the speed and the resolution of these detecting methods are treated for various conditions. T h e m exist also thrco non-photographic picture-making methods; the fluoroscopic method which uses a fluorescent material sensitive to neutrons; the neutron image intensifier proposed rather early, which operates on the same principle as an X-ray image intensifier (it uses, however, neutrons rather than X-rays to produce electron emission from an electroemissive layer combined with a neutron-sensitive fluorescent material); and the multi-wire spark technique. This latter uses a series of wires under a high potential which is activated by Boron 10 to make it responsive to neutron radiation. Boron emits a-particles upon neutron bombardment and the ~-partlcles produce sparks which give a spark image of the intensity distribution of the neutron radiation. The potentialities of these three methods are discussed. A special chapter is devoted to thermal neutrons, and the various methods useful in this type of work. Finally, the capabilities and applications of neutron radiography are outlined in a very useful chapter. This is most interesting for those who wish to obtain infor-

VoL 2s2. No. t. Julr t ~

marion and a feeling for the potentiality of this new tool of research. The indicated potentialitice, however, are rather disappointing from a general point of view. Eight applications are mentioned in such special fields as reactor, rocket and missile technology. Others are mentioned, but they too, are rather specialised, except one. is the study of thin biological specimens. With respect to this application, the author however adds the rather discouraging remark, that application of neutron radiography in the biological area has yet to be proven. The reviewer believes that the author is too peadmietic in this respect. This belief is h a ~ d on the introductory picture of this book which prments quite a good neutron radiographic picture of a grp-aqhopper. This book gives a good introduction to the field of neutron radiography and should help to foster the application of neutron photography in the biological field, an application which is also important to develop, H, ~ALT.tCANN Radiation and 8olid 8tat~ Laboratory New York University, New York LATTXC~. D ~ c T s IN QUENCHED M~'ALS, edited by R. M. J. Cotterill, M. Doyams, J. J. Jackson and M. Meshii. 807 pages, 6 X 9 in., New York and London, Academic Press Inc., 1965. Price, $22.00. The organizers of this international conference held at Argonne National Laboratory in June 1964, gathered together about a hundred scientists actively involved in lattice defects in quenched metals. They attempted by both review and research type papers to bring the subject "up-to-date" and to present a comprehensive survey of this well defined field of study. To all appearances they have succcedecl, although one has to struggle through over 800 pages to cover the whole story. I t is no criticism of the objectives of the conference that a casual reader becomes immediately aware that in rmpect to the metals considered the subject matter is very unbalanced. Well over 90 per cent of the book is concerned with face-centered cubic metals and, in particular, with copper, gold and aluminium. The fact that 650 pages are devoted to three metals with a common crystal structure suggests that the subject is far from exhausted and that there is ample scope for further work and future conferences.

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Book Redew8 Large sections of the book are given to reviews of subjects such as activation energy calculations and experiments on individual vacancies and vacancy complexes; geometry of vacancy clusters, including di and tri vacancies, voids, discs, dislocation loops and tetrahedra; annealing out of vacancies; and effect of vacancies on mechanical properties. In common with many conference proceedings the contents often overlap and in this particular book the overlap is more marked than usual. No doubt the editors did not feel able to restrict Seeger, K. Wilsdod or Maddin, for instance, but they would have done the reader a service had they insisted on a much reduced presentation. Some idea of the repetition which has occurred can be obtained from the author index. This reviewer's own meager flirtation with this subject is heralded by 4 rows of page reference numbers, and Koehier's contributions require 34 rows of numbers. However, many of the reviews are excellent and provide extremely detailed and critical appraisals. Probably the most outstanding contributions to the subject in recent years have been achieved by using transmission electron microscopy to study the shape, size and distribution of defect clusters. This is covered elegantly and in great detail by many authors and the book is full of pretty pictures; a big improvement over the "black death" of seven years ago, although the impression is left that new varieties of 'qaiack death" are being discovered regularly. A most useful feature of the book is a well edited record of the discussion periods which followed the presentation of each paper. Discussion is often the most valuable part of a conference, provided the printed version is reduced to a basic minimum. This has been achieved most effectively and many of the questions one would like to ask, having read the paper, are answered in the discussion. This book is well prepared with an extensive index coveringsubjects and authors separately. It is strongly recommended to those working in the field of point defects in metals and to those involved in advanced graduate and post-graduate teaching of this subject. DEREK HULL

Department of Metallurgy University oJ Liverpool Liverpool, England

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METALLURGICAL ACH~VEMENTS, edited by W. 0. Alexander. 330 pages, diagrams, illustr., 6 X 9 in. New York, Pergamon Press, Inc., 1965. Price, $12.75. This is a collection of fifteen papers presented in connection with the sixtieth anniversary year of the Birmingham (England) Metallurgical Society. The subject matter is varied, intended to state the position as of 1963-1964 concerning the application of metals and alloys and to highlight recent research and development of particular interest to the Midlands. Some of the invited contributors complied more rigidly to these guidelines than did others. On the research side, G. V. Raynor reviews the electron theory of metals, pointing up the limited addition to knowledge in this area in the recent past. He is of the opinion that orbital theories, combined with ligand field theory, so successful in steriochemistry, should be a topic of serious study in the next stage of development of the theory of metals and alloys. A. H. Cottrell's paper deals with the ultimate mechanical properties of solids and the design of stronger and tougher materials based on an understanding of mechanical properties. Recognizing that a maximum tolerable working elastic strain in engineering structures is about 0.02, a reasonable target for a practical, strong material of the future is about tenfold better than can be achieved with today's materials. In reaching for the new materials, the dilemma of weakness in ductile substances by dislocation propagation and in brittle materials by the propagation of cracks must be compromised. Fiber strengthening is a promising approach to material improvement. Considering structural steel and its applicability, M. R. Home discusses economies that can be effected by plastic design. This concept makes more rational use of reserves of strength associated with a material's ductility than does the more conventional elastic design. H. W. G. Hignett's discussion of the commercial production of some high temperature, nickel-base alloys is one of the applicationoriented papers. He opens with an excellent, highly condensed, historical review of the Nimonic Alloys and follows with a description of the Hereford works of Henry Wiggin and Co., Ltd. which he characterizes as "the only

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