Compositional optimization of Mg–Sn–Al alloys for higher age hardening response

The effect of Al additions and microalloying on the age hardening response of Mg–Sn alloys has been investigated to optimize the composition for the highest age hardening response. The addition of 3 at%Al lead to the best enhancement in peak hardness being 72 HV at 200 °C. The age hardening response was further enhanced from 73 to 81 HV by microalloying with 0.5 Zn, leading to the optimized alloy composition of Mg–2.2Sn–3Al–0.5Zn (at%) or Mg–9.8Sn–3.0Al–1.2Zn (wt%), i.e., TAZ1031. The enhancement in the peak strength and aging behavior is attributed to the solid solution hardening due to Al, the refinement of the Mg2Sn precipitates, the occurrence of Mg17Al12 precipitates, and the increase in the number density of non-basal Mg2Sn precipitates.