Reaction rate theory perspectives on some problems in materials science
- PDF / 1,891,984 Bytes
- 16 Pages / 613 x 789 pts Page_size
- 10 Downloads / 211 Views
INTRODUCTION
IT seldom happens that the techniques of one branch of natural science prove devoid of any potential application in another. For example, a few years ago, we were able to show that the small polaron theory t~] of solid-state physics provided a very useful formalism within which to describe the seemingly quite distinct chemistry problem of nonradiative transitions ~2] in large molecules. Again, theories of ultrasonic attenuation in metals ~3,4~were found to be readily generalized to yield estimates of the nonlinear elasticity and ,the electronic contributions to the dislocation drag coefficient. [5,6] Furthermore, and in a highly topical vein, it has recently been established by others t7] that the generalized valence bond method of quantum chemistry can reveal valuable insights into an electron pairing mechanism that may prove to be the driving force responsible for the remarkable properties of the new high-temperature ceramic superconductors, tsi Thus, it should come as no surprise that the field of radiation effects, which evolved from the applications of chemical rate theory to postirradiation defect annealing and precipitation studies, should subsequently have been developed to the point where it is now capable of offering significant new perspectives on some longstanding, but previously incompletely characterized, processes in materials science and chemistry. The intent of this article is to summarize the nature of these newly developed points of view and, in the process, to substantiate a claim of the organizers of this symposium, namely, that radiation-enhanced materials science is indeed a viable and thriving entity. A.D. BRAILSFORD is with the Physics Department, Ford Motor Company, P.O. Box 2053, Dearborn, MI 48121-2053. This paper is based on a presentation made in the symposium "Irradiation-Enhanced Materials Science and Engineering" presented as pal1 of the ASM INTERNATIONAL 75th Anniversary celebration at the 1988 World Materials Congress in Chicago, IL, September 25-29, 1988, under the auspices of the Nuclear Materials Committee of TMS-AIME and ASM-MSD. METALLURGICAL TRANSACTIONS A
The central aspect of point defect physics that irradiation brings to the fore is particle production. This feature is somewhat latent in the earliest theories of annealing, since it resides only in the incorporation of the effects of the inverse process, thermal emission, from the various internal sites of defect loss (e.g., dislocations, gas bubbles, grain boundaries, etc., hereafter referred to collectively as "sinks"). Such a process is vitally important, sink by sink, in order to allow the detailed balance of reactions demanded by the general requirements of thermal equilibrium (we shall return to this topic shortly). Nevertheless, the full consequences of point defect production events did not receive completely adequate attention until the period following the first experimental encounter tg] with the void swelling problem, a discovery that indicated the severe obstacles ahead for fast reactor develop
Data Loading...
