Effects of High Pressure on Fe-Rich Phases and Mechanical Properties of Al-14Si Alloys with Rheo-Squeeze Casting

摘要

The influence of high pressure and manganese on Fe-rich phases (FRPs) and mechanical properties of Al-14Si-2Fe alloy with rheo-squeeze casting (RSC) were investigated. The semi-solid alloy melt was prepared using ultrasonic vibration (UV), then formed by squeeze casting (SC). Results shows that the FRPs in as-cast Al-14Si-2Fe-(0.4,0.8)Mn alloys with SC are composed of coarse plate-shaped δ-Al_4(Fe,Mn)Si_2, long needle-shaped β-Al_5(Fe,Mn)Si and bone-shaped α-Al_15(Fe,Mn)_3Si_2 phases when the pressure is 0 MPa. During the solidification of the alloys with RSC, the FRPs are first refined by UV, then furtherly refined as the pressure increases. With RSC, the FRPs in Al-14Si-2Fe-0.8Mn alloy are finer and rounder than that of the Al-14Si-2Fe-0.4Mn alloy under the same pressure. The FRPs in RSC Al-14Si-2Fe-0.8Mn alloy are mainly granular particles with an average diameter of about 12 μm under 300 MPa. For the alloy with the same composition, the ultimate tensile strength (UTS) of RSC sample is higher than that of the SC sample. Under the same forming process, the UTS of Al-14Si-2Fe-0.8Mn alloy is higher than that of the Al-14Si-2Fe-0.4Mn alloy.