The course of the peritectic transformation in the Al-rich Al-Fe-Mn-Si alloys

In this work, an analysis of the course of the peritetic transformation L + Al3Fe → α-AlMnFeSi in Al-Fe-Mn-Si alloys containing an increasing Mn content (0-2%) has been presented. The particular steps of the solidification of the examined alloys by peritectic transformation: (1) primary phase precipitation from liquid alloy: L → L1 + Al3Fe, (2) peritectic reaction: L + Al3Fe → α-AlMnFeSi, (3) peritectic transformation: Al3Fe → α-AlMnFeSi ← L1 and (4) nucleation and growth of the equilibrium phase in liquid: L → L2 + α-AlMnFeSi, have been identified and described. The distribution of the transition metals Fe and Mn in the intermetallic phases has been estimated by means of the EDS microanalysis. Composition gradient in the secondary α-AlMnFeSi phase was analysed as a result of the local transport of the alloy components during the precipitation sequence. It was stated that Mn atoms involved mechanism of the analysed peritetic transformation. The formulated equation Δxα2/t = K(Mn, ΔMn) for isothermal conditions of the analysed transformation has represented a good agreement to the experimental data in the range of the low Mn content (Mn ≤ 1%).