Effect of annealing on microstructure evolution and age-hardening behavior of dilute Mg–Al–Ca–Mn alloy

Microstructure evolution and mechanical properties of the as-drawn dilute Mg-0.8Al-0.1Ca-0.6Mn (wt. %) alloy wires during annealing and peak-aging treatment were investigated in this paper. The results show that the high density of nano-sized Al–Mn precipitates strongly hindered grain boundary migration to restrict grain growth during annealing under 300 °C and 400 °C, while grain growth was obvious and the uniformity of recrystallization grain size increased due to partial dissolution of Al–Mn precipitates at 500 °C. In addition, there was a growth preference in grains with (0001) <2 1¯1¯ 0> orientation, which was closely associated with the texture changes. The alloy annealed at 500 °C for 10min exhibits remarkable age-hardening response and both the tensile yield strength and elongation to failure were improved simultaneously after peak-aging treatment, which was mainly attributed to the monolayered Guinier-Preston (G.P.) zones and planar Al2Ca precipitates.