Effects of the Fe/Mn weight ratio and cooling rate on the area fractions of α-AlFeSi and β-AlFeSi phases in Al-7.5Si-3.75Cu-0.5Mg-0.55Fe-xMn aluminum alloy

The effects of the Fe/Mn weight ratio (1,42 or 3,05) and cooling rate (0,1, 0,2, 0,5, or 0,6 °C/s) on the area fraction of α-AlFeSi and β-AlFeSi intermetallic compounds in Al-7.5Si-3.75Cu-0.5Mg-0.55Fe-xMn aluminum alloy were studied. It was found that the difference between the formation temperature of the β-AlFeSi phase and the formation temperature of the eutectic Al-Si may determine the possibilities of β-AlFeSi elimination/reduction by increasing the cooling rate

The influence of Fe, Mn and Cr addittions on the formation of iron-rich intermetallic phases in an Al-Si die-casting alloy

The microstructure evolution of a high-pressure die-cast AlSi9Cu3(Fe) alloy is studied over different Fe, Mn and Cr content. Fe-rich intermetallic phases were characterized by using optical microscope, image analysis, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS). The results revealed that the amount of Fe-rich phases as well their size increase by increasing the elemental content. Needle-like particles appear in the alloy with higher Fe:Mn ratio, while coarse \u3b1-phases assume polygonal, stark-like or Chinese script morphology according to the Fe:Mn:Cr balance as revealed by EDS analysis. The 3D-SEM investigation suggests that both the polygonal and stark-like morphology can be associated to a rhombic dodecahedron structure. The morphology evolution of the Fe-bearing particles as a function of the chemical composition and casting process is proposed and discussed

Formation of the Fe-Containing Intermetallic Compounds during Solidification of Al-5Mg-2Si-0.7Mn-1.1Fe Alloy

© The Author(s) 2018. Iron (Fe) is the most common and the most detrimental impurity element in Al alloys due to the formation of Fe-containing intermetallic compounds (IMCs), which are harmful to mechanical performance of the Al-alloy components. In this paper we investigate the formation of Fe-containing IMCs during solidification of an Al-5Mg-2Si-0.7Mn-1.1Fe alloy under varied solidification conditions. We found that the primary Fe-containing intermetallic compound (P-IMC) in the alloy is the BCC α-Al15(Fe,Mn)3Si2 phase and has a polyhedral morphology with {1 1 0} surface termination. The formation of the P-IMCs can be easily suppressed by increasing the melt superheat and/or cooling rate, suggesting that the nucleation of the α-Al15(Fe,Mn)3Si2 phase is difficult. In addition, we found that the IMCs with a Chinese script morphology is initiated on the {1 0 0} surfaces of the P-IMCs during the binary eutectic reaction with the α-Al phase. Both the binary and ternary eutectic IMCs are also identified as the BCC α-Al15(Fe,Mn)3Si2 phase. Furthermore, we found that the Fe content increases and the Mn content decreases in the Fe-containing intermetallic compounds with the decrease of the formation temperature, although the sum of the Fe and Mn contents in all of the IMCs is constant.EPSRC Grant EP/H026177/1