Effects of Al and Zn additions on mechanical properties and precipitation behaviors of Mg–Sn alloy system

For the Mg–Sn–Al alloys, the ultimate strength (UTS) of an extruded Mg–9wt.%Al–2wt.%Sn alloy reached 390MPa. TEM observation indicated that plate-like Mg17Al12 precipitates having Burgers orientation relationship with the matrix are responsible for the strength. This alloy also exhibits an age hardening behavior: the peak hardness appears after 15–20h of heat treatment at 473K. On the other hand, the UTS of the Mg–Mg–Sn–Zn alloys are on the order of 300MPa. The precipitates in these alloys are composed of the Mg2Sn and MgZn2 particles. It was found that these phases often precipitate together, suggesting that the MgZn2 phase can act as a nucleation sites for Mg2Sn. [Display omitted] ►Hardness of Mg–Sn alloy system increases with an increase in Al additions. ►Mechanical properties are improved by adding a small amount of Mn element. ►Zn element is effective to increase strength of Mg–Sn alloy system. ►MgZn2 and Mg2Sn particles coexist in Mg–Sn-Zn alloys.