Effects of high pressure rheo-squeeze casting on Fe-containing intermetallic compounds and mechanical properties of Al-17Si-2Fe-(0, 0.8)V alloys

The effects of high pressure rheo-squeeze casting (HPRC) on Fe-containing intermetallic compounds (FIMCs) and mechanical properties of Al-17Si-2Fe-(0, 0.8)V alloys were studied. The melt of alloys was treated by ultrasonic vibration (UV), then the melt was formed by high pressure squeeze casting (HPSC). The results show that irregular polygonal AlFeVSi phase is formed when 0.8%V is added into the Al-17Si-2Fe alloy. When the pressure is 0 MPa, the FIMCs in HPSC alloy are coarse plate-like or long needle-like. The coarse FIMCs are fractured as the pressure is increased to 100 MPa. The degree of fragmentation is enhanced with the increase of pressure from 100 MPa to 300 MPa. When the pressure is 0 MPa, the FIMCs in HPRC alloys are refined significantly, and the size of block-like δ phase and short needle-like β phase are decreased furtherly as the increase of pressure. For the alloy with the same composition, the ultimate tensile strength (UTS) of HPRC sample is higher than that of the HPSC sample under the same pressure. The UTS is increased with the increase of the pressure irrespective of whether there is UV or not. With HPSC, the UTS of Al-17Si-2Fe-0.8 V alloy samples is increased by 4.6%, 7.1%, 7.4% and 7.3% respectively compared with that of Al-17Si-2Fe-0V alloy samples under 0, 100, 200 and 300 MPa. With HPRC, the UTS of Al-17Si-2Fe-0.8 V alloy samples is increased by 5.4%, 4.3%, 6.3% and 6.2% respectively compared with that of Al-17Si-2Fe-0V alloy samples under 0, 100, 200 and 300 MPa.