Effect of neodymium, gadolinium addition on microstructure and mechanical properties of AZ80 magnesium alloy

The microstructure and mechanical properties of AZ80 magnesium alloys with varying Nd, Gd contents were investigated. The results revealed that the as-cast microstructure of AZ80 alloy was composed of α-Mg matrix and divorced eutectic β-Mg17Al12 phases. The fraction of Mg17Al12 phase was reduced when 0.6 wt.% Nd was added, and new rod-shaped Al11Nd3 phase and small block-shaped Al-Nd-Mn phase appeared. With Gd addition, the Gd elements mixed with Nd to form rare earth phases. New block-shaped Al2Gd and Al2Nd phases which were collectively called Al2RE phases were observed in the microstructure with more than 0.6 wt.% Gd addition. Moreover, the addition of Gd could promote the precipitation of block-shaped Al2RE phase, and inhibit the original rod-shaped Al11Nd3 phase. The AZ80-0.6Nd-0.6Gd alloy exhibited the optimal mechanical properties among all the experimental alloys, in which the tensile strength, yield strength and elongation were 215, 145 MPa and 8.33%, respectively.