Development of high-strength high-speed-extrudable Mg–Al–Ca–Mn alloy

Abstract

We investigated the effect of Al content on tensile property and microstructure of Mg–(0.6, 1.1, 1.6)Al–Ca–Mn (wt.%) alloys extruded at an extraordinary high die-exit speed of 60 m/min. All the extruded alloys showed fine grain structure with strong alignment of (0001) planes parallel to the extrusion direction. Especially, the sample containing 1.6 wt.% of Al had stronger alignment of (0001) planes than that of the other alloys. The alloy with 1.6 wt.%Al exhibited the highest ultimate tensile strength of 311 MPa and the proof stress of 284 MPa. However, the addition of 1.6 wt.% Al formed coarse Al–Mn particles and resulted in the low elongation of 16% compared to the other samples. Although the addition of 1.1 wt.% of Al also resulted in the formation of Al–Mn particles, the particle size was smaller, and their number density was lower than those in the sample containing 1.6 wt.% of Al. Therefore, high ultimate tensile strength of 297 MPa, proof stress of 263 MPa, and large elongation of 24% were simultaneously achieved in the sample containing 1.1 wt.% of Al.