Cleavage fracture in face-centred cubic metals

Abstract

Observations of cleavage fracture in some fcc materials are briefly described. The results suggest that cleavage fracture is not an ‘atomically brittle’ process but occurs by alternate slip at crack tips in conjunction with formation of very small voids ahead of cracks. It is proposed that environmentally induced cleavage of normally ductile materials (during liquid-metal embrittlement, hydrogen assisted cracking, stress-corrosion cracking, and corrosion fatigue) can be explained on the basis that chemisorption of environmental species facilitates nucleation of dislocations at crack tips.