Effect of severe plastic deformation on tensile properties of a cast Al–11 mass% Si alloy

Up to now, investigations for the effect of the severe plastic deformation on mechanical properties of the processed materials are not enough. In the present work, tensile properties of a cast Al–11 mass% Si alloy processed by rotary-die equal-channel angular pressing (RD-ECAP) with 4–32 passes were investigated at room temperature. Elongation to failure significantly increased with the number of RD-ECAP passes from 4 to 32. For example, the sample pressed 32 passes has 10 times higher elongation (∼15%) than the as-cast alloy (∼1.5%). These results show that the cast Al–11 mass% Si alloy was transformed into a ductile alloy by RD-ECAP. Yield strength was noticeably improved by first four passes of RD-ECAP (about 40%) compared with that of the as-cast alloy. Fine-grained microstructure of the aluminum alloy matrix (about 300 nm) and modified grain boundaries after RD-ECAP is the primary reason for exhibiting significant ductility of this alloy. Grain boundary sliding (GBS) occurred at the room temperature tensile testing in the RD-ECAPed sample. The plastic deformation and fracture mechanism of the cast Al–11 mass% Si alloy were markedly changed by RD-ECAP.