Séparations de phases dans les solutions solides métalliques

Abstract
A number of metallic alloys display phase separation between two coherent phases. This paper will describe how to characterize the dynamic evolution of a metallic solid solution quenched inside a miscibility gap. The combination of various measurement techniques allows one to obtain complementary informations on the progress of unmixing ; their interpretation will be discussed in the light of theories. The kinetics regime at the onset of unmixing depends on the depth of the quench and on the distance to the critical point : it ranges from nucleation-growth for shallow quenches away from the critical point to spinodal decomposition for deep quenches or quenches near the critical point. In the coarsening regime, the phase morphology will affect the growth kinetics. The morphology will depend on properties of the phases themselves (eg. : ordered phase), on the volume fractions, on size effects which introduce an anisotropy and modify the location of the coherent miscibility gap.