Effects of samarium (Sm) additions on the microstructure and mechanical properties of as-cast and hot-extruded Mg-5 wt percent Al-3 wt percent Ca-based alloys

摘要

Samarium (Sm) additions to as-cast Mg-5Al-3Ca-based alloys result in changes, such as equiaxed grains and a refined grain size. The microstructure of as-cast Mg-5Al-3Ca-xSm alloys consists of an alpha-Mg matrix, a (Mg, Al)_2Ca eutectic phase, and an Al_2Sm intermetallic compound. In as-cast alloys, the (Mg, Al)_2Ca eutectic phase was located at grain boundaries with a chain structure, and the Al_2Smintermetallic compounds were homogeneously distributed at the alpha-Mg matrix and grain boundaries. The eutectic phase of the extruded alloys was elongated in the extrusion direction and crushed into fine particles because of severe deformation during hot extrusion, and the grain size was refined with an increased amount of Sm addition. The maximum values of the yield strength and tensile strength were 313 MPa and 330 MPa at 2 wt percent Sm alloy content, respectively.