Effects of ultrasonic vibration on the iron-containing intermetallic compounds of high silicon aluminum alloy with 2% Fe

Abstract

Abstract The effects of ultrasonic vibration (USV), the combined effects of USV and the addition of Mn on the morphology of iron-containing intermetallic compounds of Al–20Si–2.0Fe–2.0Cu–0.4Mg–1.0Ni alloy have been studied respectively. The mechanism of shape-transformation of Fe-containing phases is also investigated. A large amount of long needle-like β-Al5FeSi phases accompanied with a few δ-Al4FeSi2 phases existed in the matrix of high silicon aluminum alloy with 2% Fe in traditional casting process. The effects of acoustic cavitation and acoustic streaming generated by USV which was applied near the liquidus temperature of this alloy, homogenized the solute distribution field and temperature field of the melt, lowered the concentration level of Fe atoms in solidification front, and decreased the start-freezing temperature of β phase. That the formation of acicular β phase was suppressed, contribute to enlarge the forming temperature range of δ phase of the alloy with certain time of USV imposed near the liquidus temperature. The finest δ particles and only a small amount of β phase were obtained in the matrix of the Fe-containing alloy with USV for 120 s. With the complex effects of USV and addition of 0.5% Mn, the forming of acicular β phase was almost repressed and the Fe-containing phases were in forms of fine Al4(Fe,Mn)Si2 and Al5(Fe,Mn)Si particles in the size of 20–30 μm.