Bicrystal studies of diffusion-induced grain boundary migration in Cu/Zn
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I.
INTRODUCTION
DIFFUSION-induced grain boundary migration (DIGM) is now a well-recognized phenomenon in which the sideways migration of grain boundaries accompanies the diffusion of solute along them. m This phenomenon has been reported in a wide range of metallurgical systems and some oxides. Even after nearly a decade of attention to the study of DIGM, little consensus has developed regarding the mechanism by which it occurs, and indeed this is a subject of continuing controversy. Most of the published experimental data on DIGM consist simply of reports of observations of the phenomenon in new alloy systems, and there has been relatively little systematic study. A significant exception to this kind of "stamp collecting" has been the work of Yoon and co-workers [2'3] who have investigated the effects of misfit between the solute and solvent materials, although the primary thrust of their work has been on liquid film migration rather than solid-state DIGM. Their results have shown that the migration velocity of liquid films depends upon the square of the misfit of the diffusing species in the matrix, and there is strong circumstantial evidence that the same behavior holds for DIGM in their specimens. In our systematic studies of DIGM, we have sought to investigate the effects of the grain boundary itself rather than the misfit effects studied in the absence of a solid interface. We, therefore, have used only a single system and constant diffusion conditions while we vary the grain boundary parameters. Some of our results on symmetrical tilt boundaries have been published elsewhere, ta,m and we present a summary of these and some new results on asymmetrical boundaries here. FU-SEN CHEN and GIRISH DIXIT, formerly Graduate Students, Department of Materials Science and Engineering, State University of New York at Stony Brook, are Research Staff Members, SGS Thomson Microelectronics Company, Houston, TX. ANTONIO J. ALDYKIEWICZ, Jr., Graduate Student, and A.H. KING, Vice Provost for Graduate Studies and Professor of Materials Science, are with the Department of Materials Science and Engineering, State University of New York at Stony Brook, Stony Brook, NY 11794-2275. This paper is based on a presentation made in the symposium "Interface Science and Engineering" presented during the 1988 World Materials Congress and the TMS Fall Meeting, Chicago, IL, September 26-29, 1988, under the auspices of the ASM-MSD Surfaces and Interfaces Committee and the TMS Electronic Device Materials Committee. METALLURGICAL TRANSACTIONS A
II.
EXPERIMENTAL
A series of copper bicrystals containing [100] tilt grain boundaries was grown by the Bridgman technique. The misorientations were rechecked after growth by means of Lane back reflection X-ray diffraction. Individual specimens were cut from the bulk bicrystals in the form of slices approximately 2-mm thick, with their planes either perpendicular to the tilt axis, as indicated in Figure 1, or parallel to it. Each specimen was polished to remove any surface damage layer in order to suppr
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