Microstructure, tensile properties and creep behaviors of as-cast Mg-2Al-1Zn-xGd (x=1, 2, 3, and 4 wt.%) alloys

The microstructure, tensile properties and creep behaviors of as-cast Mg-2Al-1Zn-xGd (x = 1, 2, 3, and 4 wt.%) alloys have been investigated. The results indicated that the addition of Gd led to the formation of a branched (Mg, Al)(3)Gd phase and a cubic Al2Gd phase. The tensile properties of the AZ21 alloy have been improved greatly at both room temperature and elevated temperature due to the presence of the branched (Mg, Al)(3)Gd phase. The AZ21 alloy containing 4% Gd presented a good creep-resistant property. The steady-region and the total creep strain of the alloy after 100 h were 2.6 x 10(-8) s(-1) and 1.2%, respectively. The enhancement of creep properties of the AZ21 alloy was mainly ascribed to the thermal stable branched (Mg, Al)(3)Gd phase by which the movement of dislocations were impeded effectively. (C) 2012 Elsevier B. V. All rights reserved.