Effect of microalloyed Al and Ca on mechanical properties and corrosion resistance of high-speed extruded Mg-2Zn-1Mn (mass%) alloy

Abstract

Mechanical properties and corrosion resistance of high-speed extruded Mg-2Zn-1Mn (mass%) alloys microalloyed with Al and/or Ca were evaluated. The microalloying of Al improved the tensile yield strength, while the compressive yield strength remained unchanged, which deteriorated the yield anisotropy. The Al addition also deteriorated the corrosion resistance owing to the formation of coarse βMn phases that promoted the galvanic corrosion. By the single addition of Ca, both tensile and compressive yield strengths increased, which led to a slight improvement of the yield anisotropy. A texture weakening, which was attributed to the single Ca addition, also improved the ductility slightly. Such property improvements were achieved without the loss of corrosion resistance. A ViscoPlastic Self-Consistent simulation revealed that the single Ca addition was effective for the hardening of both basal and prismatic slips, which improved the yield strength in both tension and compression. • Microalloyed ZM21 alloys were extrudable at a high speed of 60 m/min. • Single Ca addition was effective in improving tensile and compressive properties. • Al addition increased yield anisotropy in tension and compression. • Al addition promoted micro galvanic corrosion.