Microstructure and mechanical properties of Mg–Al–Sn extruded alloys

Abstract

Mg–Al–Sn alloys are being developed as a new series of magnesium alloys due to their good creep resistance, ductility and high temperature properties. The Mg–Al–Sn alloys containing low Al/Sn-content may have potential as a high-ductility wrought magnesium alloy. However, the effect of composition on the microstructure and mechanical properties of wrought Mg–xAl–ySn alloys have received little attention. In the present work, Mg–xAl–ySn–0.3Mn (x = 1, 3, 6 and y = 1, 3) alloys have been prepared by hot extrusion at temperatures from 523 K to 623 K. The experimental results reveal that the yield strength of the as-extruded alloys is sensitive to Al content and extrusion temperature, but insensitive to Sn content. The yield strength increases with decrease Al content or extrusion temperatures. The Mg–1Al–ySn–0.3Mn (y = 1, 3) alloys extruded at the temperatures ≤573 K exhibit the relative higher yield strength in this paper (the yield strength exceed 250 MPa with elongation of about 20%). The relative high strength is mainly attributed to the formation of fine recrystallized grains and high fraction of coarse un-recrystallized grain regions which show strong (10-10) and (0001) textures. The orientation relationship between the precipitated Al8Mn5 phase and the Mg matrix in the Mg–1Al–1Sn–0.3Mn alloy is also determined. And the strengthening mechanism of the alloys is discussed.