Effect of HCPEB Treatment on Microstructure and Microhardness of Hypereutectic Al-20Si Alloy

摘要

The paper reports, for the first time, effect of HCPEB treatment on microstructure and microhardness of hypereutectic Al-20Si alloy. Microstructure characteristics of modified layer are analyzed by SEM and XRD. SEM results show that primary Si is solid dissolved in Al matrix and forms Al-Si supersaturated solid solution on top melted layer induced by HCPEB treatment. It can be seen that both primary Si particles merge one large primary Si particle due to diffusion of Si element. XRD analysis shows that lattice parameters of Al decrease and lattice distortion increases after HCPEB treatment. Microhardness test results suggest the surface microhardness of primary Si presents gradient distribution from center to edge after HCPEB treatment, and the microhardness of center of primary Si decreases with increase of pulse number. It is demonstrated that the HCPEB technique has a good application future in treating coarse primary Si of hypereutectic Al-Si alloys.