Microstructures and Thermal Properties of Mg–Sn–Ca Alloys: Casts and Extrusions

Microstructure and thermal properties of Mg–(3 mass% or 5 mass%) Sn–2 mass% Ca alloys as casts and extrusions have been investigated with different ram speeds and extrusion temperatures. Mg–(3 mass% or 5 mass%) Sn–2 mass% Ca alloys are composed of α -Mg, MgSnCa, and Mg 2 Ca phases. By adding Sn content from 3 mass% to 5 mass%, the MgSnCa phase is increased and the Mg 2 Ca phase is decreased. During hot extrusion, the average grain sizes are increased with increasing ram speed and temperature. The ultimate tensile strength ( UTS ) and elongation for the Mg–5Sn–2Ca alloy at 2.3 mm · s - 1 are 227.73 MPa and 18.43 %, respectively. With increasing extrusion ram speed, the UTS and elongation for the Mg–5Sn–2Ca alloy are remarkably decreased to 215.95 MPa, 206.33 MPa, and 14.74 %, 6.88 %, respectively. The thermal conductivity for the Mg–3Sn–2Ca alloy is dramatically improved, compared to commercialized Mg alloys such as AZ31 and AZ91 due to formation of MgSnCa and Mg 2 Ca phases.