CHEMICAL ASPECTS OF BRITTLE-FRACTURE - GRAIN-BOUNDARY SEGREGATION

The relationship between brittle fracture and chemical composition of grain boundaries is documented by the study of solute segregation in F e-Si base alloys. Si, P and S segregation at the {013} symmetrical gra in boundary in an Fe-6at.%Si alloy induce a small decrease of the cohe sion energy, During brittle intergranular separation, segregants atoms are distributed between the two fracture surfaces. This distribution is homogeneous in the case of symmetrical boundaries but uneven for as ymmetrical ones as shown in numerous examples and reflects asymmetry o f sites in grain boundary core available for segregation. (C) 1997 Els evier Science S.A.