Effects of Mn addition on the microstructures, mechanical properties and work-hardening of Mg-1Sn alloy

Mg-Sn-Mn-based alloys exhibit great application prospect because of their high mechanical properties and good creep resistance. The content of Mn in Mg-Sn-based alloys is commonly less than 1 wt%. In this study, the effect of Mn addition on the microstructure, mechanical properties and work-hardening behavior of Mg-1Sn (wt%) alloys has been investigated. The as-extruded alloys are mainly composed of alpha-Mg and Mn precipitates, which exist in TM11 and TM12. The average grain size sharply decreases with Mn addition. In addition, with increase in Mn content, the basal texture of the alloys has strengthened. The experimental results show that Mn addition significantly increases the tensile and compressive yield strengths, ultimate tensile strengths, and elongation of the as-extruded Mg-Sn-Mn alloys because of the good microstructures. Moreover, the decrease of number of tensile twins in compress leads to the yield asymmetry reduces with Mn addition. With increasing Mn content, the value of work-hardening exponent and capacity decreases, the work-hardening behavior in stage III significantly improved. The variation in microstructures, mechanical properties and work-hardening of Mg-Sn-Mn alloys have been analyzed.