Cu-Ag Solid Solutions Formation and Properties upon Severe Plastic Deformation

A number of nonequilibrium nanocrystalline fcc solid solutions Cu1-x-Agx (x = 0,1; 0,2; ... 0,9; 1,0) were obtained by mechanical alloying of powders by the use of high pressure torsion. Chemical homogeneity, microstructure, mechanical properties and thermostability were studied. The obtained alloys were found to be characterized by a positive excess over Vegard law, ~ 20 nm grain sizes, a microhardeness of 4.5-6 times higher than the Cu and Ag one and brittle type of the fracture surface. In situ shear stress vs. strain measurements and energy-power parameters estimation were performed. A decomposition of nonequilibrium solid solution induced by a thermal influence begins from close to room temperatures and finishes completely at heating up to 500°С accompanied by collective recrystallization development.