Effect of double aging and microalloying on the age hardening behavior of a Mg-Sn-Zn alloy

摘要

We have investigated the effect of double aging and microalloying on the age hardening behavior of a Mg-2.2Sn-0.5Zn alloy. The double aging at 473 K after pre-aging at 343 K lead to an increased peak hardness to more than 80 HV as a result of the refinement of the polygonal Mg_2Sn precipitates by the heterogeneous nucleation at densely dispersed MgZn_2 precipitates. The age hardening response of the Mg-2.2Sn-0.5Zn alloy was further enhanced by microalloying with 0.2Cu (at.%), 0.2Ca-0.2Ag-0.2Zr or 1.0A1. In particular, the peak hardness of the Mg-2.2Sn-0.5Zn-l .0A1 alloy was 95 HV at 433 K, which was attributed to the synergy effect of the dispersion of the fine rod and polygonal Mg_2Sn precipitates and solution hardening with Al.