Dislocation-particle interactions during high temperature deformation of two-phase aluminium alloys

Aluminium-silicon, and aluminium-nickel alloys containing various dispersions of secondphase particles have been deformed in compression at elevated temperatures. It is found that there is a sharp transition in the mechanical behaviour, microstructure, and microtexture, at a critical temperature or strain rate, which is dependent on particle size. The results are compared with various models of stress relaxation at particles, and it is shown that both interface and bulk diffusion controlled mechanisms are operative. The relevance of the transition to the hot working of two-phase alloys is discussed.