Synergistic effects of alloying, homogenization, and hot extrusion on the mechanical properties of as-cast Mg-Al-Ca magnesium alloys

Synergistic effects of partial replacement of Al with Ca, homogenization heat treatment, and hot extrusion on the microstructure and mechanical properties of Mg-(7-x)Al-xCa magnesium alloys were studied. The Mg17Al12 compound in Mg-7Al alloy, Mg17Al12 and Al2Ca compounds in AX52 alloy, Al2Ca and Mg-Al-Ca compounds in AX43 alloy, and Mg-Al-Ca compound in AX25 were characterized. The as-cast alloys were quite brittle with low strength values due to the deleterious effects of the continuous intergranular brittle constituents that completely masked the alloying effect. Homogenization resulted in the spheroidization of the eutectic constituents and gave the alloys some tensile ductility, which was remarkable for the AX43 alloy due to its fine grain size. Hot extrusion resulted in the fragmentation and dispersion of particles as well as formation of equiaxed, fine microstructures by the recrystallization processes, which led to the profound enhancements of the tensile properties in terms of both strength and elongation to failure. The product of strength and ductility of similar to 5500 MPa.% for the extruded AX43 alloy was far better than the value of similar to 314 MPa.% for the as-cast counterpart.

Automated summary

The synergistic effects of partial replacement of Al with Ca, homogenization heat treatment, and hot extrusion on the microstructure and mechanical properties of Mg-(7-x)Al-xCa magnesium alloys were studied. Homogenization resulted in eutectic constituents spheroidization and tensile ductility improvement, while hot extrusion led to fragmentation and dispersion of particles, formation of fine microstructures, and profound enhancements of tensile properties. The extruded AX43 alloy showed significantly better product of strength and ductility compared to the as-cast counterpart.