Needle Like Fe-Containing Intermetallic Compounds of High Silicon Aluminum Alloy with Fe Modified by Mn and Ultrasonic Vibration
In this study, the modification effects and mechanism of manganese (Mn) and ultrasonic vibration (USV) on the needle-like Fe-containing intermetallic compounds of Al-20Si-xFe-2.0Cu-0.4Mg-1.0Ni (x=1, 2 wt.%) alloy have been studied respectively. The effect of Fe-containing phases on volume fraction of hard phases is also investigated. The results show that the mechanism and effect of Fe-containing intermetallic compounds improved by Mn are in close relationship with Fe content. Mn can promote to form less harmful α-Al15(Fe,Mn)3Si2 phase, or replace some Fe atoms of β-Al5FeSi and δ-Al4FeSi2 according to different Fe content. When USV was applied to this alloy containing 2%Fe near liquidus temperature, most of the acicular β phases formed in traditional process are substituted by fine plate δ phases. With the combined effects of 0.5%Mn and USV, the acicular β phases are almost repressed and the Fe-containing phases exist in form of fine Al4(Fe,Mn)Si2 and Al5(Fe,Mn)Si particles about 20~30μm. Consequently, the total volume fraction of hard phases which are composed of primary silicon particles and Fe-containing phases increases significantly.