CHEMISTRY AND BONDING CHANGES ASSOCIATED WITH THE SEGREGATION OF BI TO GRAIN-BOUNDARIES IN CU

Grain-boundary embrittlement, caused by the segregation of impurity an d alloying elements, occurs in many systems and has been the focus of a large amount of research owing to its technological importance. Howe ver, the exact mechanism by which the segregating elements cause embri ttlement remains unclear. In this paper the localized changes in the e lectronic structure in the classical embrittling system of Bi in Cu ha ve been studied. Experimental results were obtained by examining the f ine structure in the electron spectrum which was then compared to calc ulations using the layer Korringa-Kohn-Rostoker (LKKR) method. A chang e in the d density of states has been observed for the Cu atoms at the grain boundary, associated with Bi, and an electronic model to explai n embrittlement is described. (C) 1998 Acta Metallurgica Inc.