Effects of Zn additions on the microstructure and hardness of Mg-9Al-6Sn alloy

The effects of Zn additions on the age hardening response and microstructure of Mg-9Al-6Sn (wt.%) alloy have been investigated. It is found that the Zn additions can remarkably increase the alloy hardness in the as-quenched condition. The peak hardness value of the Mg-9AI-6Sn alloy increases from 90 +/- 0.87 HV to 103 +/- 3.83 HV, when the Zn addition is 3 wt.%, which is the highest among the magnesium casting alloys that are free of rare-earth elements. The enhanced hardness in the Mg-9A1-6Sn-3Zn alloy is attributable to an increased volume fraction of smaller Mg2Sn particles in the solution-treated condition and the formation of [0001](Mg) Mg17Al12 rods and Mg-21(Zn, Al)(17) precipitates in the peak-aged condition. (C) 2016 Elsevier Inc All rights reserved.