Novel Control Factor for Tensile Strength and Solidification Cracking in Partially Solidified Al–Mn–Cu Alloy Based on Campbell’s Model with Fe-Rich Intermetallic Compounds

Abstract

AbstractIn this study, the effect of the Fe-rich intermetallic compound phases (IMC) on the solidification cracking susceptibility (Hot Tearing Susceptibility, HTS) of the Al–Mn–Cu alloy and the associated controlling factors were investigated. Using the Al–1.15Mn–1.0Cu–0.5Si–0.08Ti–0.016B–0.15Fe and Al–1.15Mn–1.0Cu–0.5Si–0.08Ti–0.016B–0.4Fe alloys, the HTS and mechanical properties in the partially solidified state were experimentally obtained. As a result, the HTS decreased with the increasing Fe contents. In addition, the tensile strength of the alloys in the partially solidified state (σmax) increased with the increasing Fe contents. The fraction of solid cohesion considering the Fe-rich IMC phase (fsc IMC) based on the Campbell’s model (fsc Campbell) is proposed as the controlling factor of σmax. The fsc Campbell, which simulates the two-phases model of the α-Al and liquid phases, did not consistently demonstrate the dependence of σmax on fsc Campbell for the two alloys (σmax = f(fsc Campbell)). However, when employing the fsc IMC, which incorporates the Fe-rich IMC phase in a three-phases model, a consistent correlation is observed between fsc IMC and σmax for the two alloys (σmax = f(fsc IMC)). Therefore, it is suggested that the controlling factor influencing the change in σmax with the Fe content should be the fsc IMC. Additionally, the bonding of primary α-Al phase together with Fe-rich IMC phase that is crystallized at the grain boundary will increase σmax, contributing to the reduction of HTS.