Enhanced rate-dependent tensile deformation in equal channel angularly pressed Sn-Ag-Cu alloy

Tensile stress-strain response of an equal channel angularly pressed (ECAPed) Sn-3.8Ag-0.7Cu alloy was investigated to seek a mechanistic understanding of the time-dependent deformation in Sn-rich alloys. It was found that the deformation behavior of the ECAPed alloy had a stronger rate-dependence than the as-cast alloy. At low strain rates, the ECAPed alloy exhibited a higher ductility but a lower flow stress. During tensile deformation, the equiaxed Sn grains were stretched into thin strips. In comparison, the slip steps were primary feature within single grain at high strain rates. The enhanced rate-dependence of the ECAPed alloy was related to greater tendency for grain boundary diffusion due to the increase in the grain boundary density.