Application of rapid solidification powder metallurgy to the fabrication of high-strength, high-ductility Mg–Al–Zn–Ca–La alloy through hot extrusion

Abstract

The microstructure and mechanical properties of hot extruded Mg–7Al–1Zn–1Ca powder alloys with an addition of 1.5% La or 3.3% La were investigated. Both rapidly solidified powders, produced via spinning water atomization process, and cast billets were extruded at 573, 623 and 673 K to optimize the processing conditions for obtaining better mechanical response. Powders were consolidated using both cold compaction and spark plasma sintering. The tensile properties of the extruded alloys were then evaluated and correlated to their microstructures. The results showed that the use of rapidly solidified Mg–7Al–1Zn–1Ca alloy powders with La additions could lead to effective grain refinement and super saturation of alloying elements, which in turn resulted in the improved mechanical response. The Mg–7Al–1Zn–1Ca–1.5La alloy extruded at 573 K attained ultimate tensile strength of 450 ± xx MPa and elongation of 17 ± xx%, superior to the Mg–7Al–1Zn–1Ca–3.3La alloy and other Mg alloys like Mg–Al–Mn–Ca. This may help extend the application of Mg alloys to higher load-carrying parts while maintaining the excellent advantage of light weight.