Tensile properties of an Al–11mass%Si alloy at elevated temperatures processed by rotary-die equal-channel angular pressing

Abstract: Tensile properties of a severely deformed Al–11mass%Si alloy processed from 4 to 32 passes by rotary-die equal-channel angular pressing (RD-ECAP) were investigated at elevated temperatures. Elongation to failure significantly increased with increasing the number of RD-ECAP passes at each test temperature. The sample pressed 32 passes exhibited 34% elongation to failure at 573K, which was five times higher than that of the as-cast alloy. In addition, the RD-ECAP processed (RD-ECAPed) sample exhibited large elongation to failure at 573K even at the high strain rate. The elongation to failure of the sample pressed 32 passes was 28% at the high strain rate of 2.30×10−1 s−1 at 573K. High strain rate superplasticity was obtained in the RD-ECAP processed Al–11mass%Si alloy. The maximum total elongation of 192% was obtained at 5.75×10−1 s−1 at 788K. The strain rate sensitivity (m value) was 0.35. The obtained large elongation was related to the contribution of the grain boundary sliding (GBS). On the other hand, the RD-ECAPed specimen followed by T6 treatment exhibited high tensile strength as well as the un-pressed alloy with T6 treatment, and good plasticity at elevated temperatures, due to the homogenous distribution of the second-phase particles, the equiaxed and small grains. [Copyright &y& Elsevier]