Dynamic Compression Properties of an Ultrafine-Grained Al-26 wt.% Si Alloy Fabricated by Equal-Channel Angular Pressing

摘要

The grains of a hypereutectic Al-26 wt.% Si alloy were drastically refined by multi-pass equal-channel angular pressing (ECAP). Compression deformation characteristics of the alloy with different microstructure were examined at two dynamic strain rates (700, 1000 s(-1)) by a split-Hopkinson pressure bar system and at a quasi-static strain rate (0.001 s(-1)) by a universal testing machine, respectively. The results reveal that the Al-26 wt.% Si alloy is strain-rate sensitive under those compression conditions, i.e., the initial yield stress and the flow stress considerably increase with the strain rate. Grain refinement through ECAP improves the strain-rate sensitivity of the alloy. With rising the ECAP temperature, the yield stress of the ultrafine-grained alloy decreases but the strain value increases during dynamic compression.