Influence of zinc addition on the precipitation in Al-Mn-Zr alloys

Abstract

Two Al-Mn-Zr alloys produced by twin-roll casting having almost the same chemical composition except for the content of zinc (0.10 and 1.66 wt.%, respectively) were investigated. Precipitation reactions during two-step annealing were examined by means of electrical conductivity and differential scanning calorimetry. Furthermore, SEM quantitative particle analysis, energy dispersive spectroscopy, and electron backscattered diffraction were carried out. The results show that 1.1 to 1.8 wt.% of zinc enters into constituent Al15(Mn,Fe)3Si2 phases and that zinc improves nucleation of small Al(Mn,Fe)Si particles, 20 to 100 nm in size, which is beneficial for the recrystallization resistance of the alloy.K e y w o r d s : Al-Mn-Zr alloys, Zn addition, microstructure, SEM quantitative particle analysis, phase analysis