Diffusion-Controlled Decohesion Using a Cu-Sn Alloy as a Model System

Abstract

ABSTRACTThis research deals with a mode of brittle intergranular fracture in which a surface-adsorbed embrittling element is driven into a grain boundary as a result of the application of a tensile stress across the boundary. A Cu-8%Sn alloy has been employed to explore this phenomenon, since tin is a surface-active element, and this alloy is known to suffer intergranular weakness at elevated temperatures. Intergranular cracking occurred by brittle, discontinuous crack advance at 265°C in vacuum with an average rate of 0.1μm/sec. This behavior is analogous to sulfur-induced stress-relief cracking in steels and several cases of liquid-metal embrittlement, suggesting that this phenomenon has a generic nature.