Solidification microstructure of ZA102, ZA104 and ZA106 magnesium alloys and its effect on creep deformation

In this paper, the microstructure of slowly solidified ZA102 (Mg-10%Zn-2%Al ), ZA104 (Mg10%Zn4%Al) and ZA106 (Mg-10%Zn-6%Al) magnesium alloys was chara cterized. Thermal analysis was performed to determine the solidification ev ents which occur upon cooling. The results show that these alloys contain a lpha>(*) over bar * (Mg) and a variable fraction of intermetallic phases: i n ZA102 alloy, Mg-32(Al,Zn)(49) (tau) and MgZn (epsilon) are observed; in Z A104 alloy, tau is the only intermetallic phase formed; in ZA106 alloy, Al2 Mg5Zn2 (phi) and a small amount of the phase tau are found. It is suggested that the ternary phase tau could play an important role in the improvement of the creep resistance of alloys in the Mg-Zn-Al system. The results also show that the solidification range of these alloys decreases with an incre ase of aluminum content.