Grain-Boundary Fragility and Segregation

AbstractIntergranular embrittlement induced by equilibrium segregation of solutes is now recognized in a number of engineering alloys, particularly in ferrous systems. In such multicomponent systems, grain-boundary segregation effects can be quite complex, with competitive interactions among a number of surface-active species. Consequently, the model binary system copper-bismuth has been used here in an attempt to relate, quantitatively, grain-boundary fragility with grainboundary segregation. The experimental approach has been to measure the dependence of both the interface energies and the mechanical strength on bulk bismuth content. The results show that the brittleness is due to grain-boundary decohesion, which can be related to the adsorption of bisnluth to the grain boundaries.