The microstructure, creep resistance, and high-temperature mechanical properties of Mg-5Sn alloy with Ca and Sb additions, and aging treatment

The microstructure, creep resistance, and high-temperature shear strength of the Mg-5Sn, Mg-5Sn-1.4Ca, and Mg-5Sn-0.4Sb alloys were studied in the as-cast and aged conditions. Impression creep tests were performed at 150 and 200 oC and under punching stresses in the range 250-500 MPa. The shear yield stress (SYS) and ultimate shear strength (USS) were measured by the shear punch test (SPT) in the temperature range 25-250 oC. The results showed that creep resistance and shear strength of the base alloy were significantly enhanced with the addition of Sb and Ca. This was attributed to the concurrent formation of Mg2Sn particles with the more thermally stable CaMgSn or Mg3Sb2 phases which strengthen both matrix and grain boundaries during deformation in the investigated system. Furthermore, mechanical properties and creep resistance of the aged alloys were much better than those of the as-cast materials, due to the higher volume fraction of Mg2Sn, Mg3Sb2, and CaMgSn precipitates distributed homogeneously in the microstructure of the aged materials.