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

Tensile properties of a severely deformed Al–11 mass%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 573 K, 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 573 K 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 573 K. High strain rate superplasticity was obtained in the RD-ECAP processed Al–11 mass%Si alloy. The maximum total elongation of 192% was obtained at 5.75 × 10−1 s−1 at 788 K. 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.