RETRACTED: Intermetallic and dispersoid structures in aa3104 Aluminum alloy during two-step homogenisation (Retracted article. See MAR, 2023)

During homogenisation of the AA3104 cast ingot, a phase transformation of intermetallic particles from beta-Al-6(Fe,Mn) orthorhombic phase to harder alpha-Al-x(Fe,Mn)(3)Si-2 cubic phase occurs. The large constituent intermetallic particles, regardless of phase, assist in the recrystallisation nucleation process through particle stimulated nucleation (PSN). Ultimately, this helps to refine grain size. The sub-micron dispersoids act to impede grain boundary migration through a Zener drag mechanism. For this reason, the dispersoids that form during homogenisation are critical in the recrystallisation kinetics during subsequent rolling, with smaller dispersoids being better suited to reverse rolling mills. This work simulates an industrial two-step homogenisation practice with variations in the peak temperature of the first step between 560 degrees C and 580 degrees C. The effect of this temperature variation on the intermetallic particle-phase evolution is investigated. The aim is to identify the ideal intermetallic phase balance and the dispersoid structure that are best suited for hot rolling on a single stand reversing mill, in order to minimise recrystallisation during rolling through maximising Zener drag and maintaining galling resistance. The results indicate a trend where an increase in homogenisation temperature from 560 degrees C to 580 degrees C yields, firstly, an increase in the volume fraction of the alpha-phase particles to greater than 50% of the total volume fraction at both the edge and the center of the ingot and, secondly, it yields an increased dispersoid size. Thus, in the context of a reverse rolling operation, a lower temperature homogenisation practice produces a near-ideal combination of intermetallic particle-phase distribution, as well as dispersoid size, which is critical for Zener drag and the minimization of recrystallisation during the hot rolling processes.