Abstract:Effects of processing parameters on microstructure evolutions by mechanical stirring, procedures for obtaining thixotropy in semi-solid slurries, and procedure for thixoforging component, were investigated in hypereutectic Al-Si alloy. It is shown that 605℃was the proper temperature for stirring treatment of this alloy, at which the coarse and plate primary Si crystals were effectively changed to globular crystals with a mean diameter of 200μm after 50min stirring, that billets with excellent thixotropy were obtained after 50min remelting at 575℃, in which solid fraction of matrix and primary Si crystals was about 60%, and that a perfect near net shape component of disc casting was obtained by thixoforging.

Key words: hypereutectic Al-Si alloy; primary Si crystals; thixoforming