Nano-scale Reinforcements and Properties of Al-Si-Cu Alloy Processed by High-Pressure Torsion

To improve the comprehensive mechanical properties of Al-Si-Cu alloy, it was treated by a high-pressure torsion process, and the effect of the deformation degree on the microstructure and properties of the Al-Si-Cu alloy was studied. The results show that the reinforcements (beta-Si and theta-CuAl2 phases) of the Al-Si-Cu alloy are dispersed in the alpha-Al matrix phase with finer phase size after the treatment. The processed samples exhibit grain sizes in the submicron or even nanometer range, which effectively improves the mechanical properties of the material. The hardness and strength of the deformed alloy are both significantly raised to 268 HV and 390.04 MPa by 10 turns HPT process, and the fracture morphology shows that the material gradually transits from brittle to plastic before and after deformation. The elements interdiffusion at the interface between the phases has also been effectively enhanced. In addition, it is found that the severe plastic deformation at room temperature induces a ternary eutectic reaction, resulting in the formation of ternary Al+Si+CuAl2 eutectic.