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

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. (C) 2015 Elsevier B.V. All rights reserved.