Microstructure and mechanical properties of as-cast and as-hot-rolled novel Mg-xSn-2.5Zn-2Al alloys (x=2, 4 wt%)

Two novel Mg-Sn based wrought alloys are developed with good mechanical properties, which are Mg-2Sn-2.5Zn-2Al (TZA222) alloy and Mg-4Sn-2.5Zn-2Al (TZA422) alloy. The as-cast alloys with high elongations to failure over 10% and low tensile strengths just over 70 MPa are suitable for hot deformation processing. After hot rolling at 350 degrees C of 60% total reduction, the strengths of the alloys are significantly improved, meanwhile, their elongations to failure still remain at high level. The as-hot-rolled TZA422 alloy has better mechanical properties, of which the yield strength, ultimate tensile strength and elongation to failure are 196.9 MPa, 285.5 MPa and 20.7%, respectively. It has nano-sized Mg2Sn particles dispersed within fine grains with an average size of 10 gm, while the main second phase is coarse Mg5Zn2Al2 in the as-cast TZA422 alloy. Both the as hot-rolled TZA422 and TZA222 alloys have good combinations of strength and ductility, which are comparable to other as-hot-rolled Mg alloys with high performances.