Effects of precipitates on grain size and mechanical properties of AZ31-x% Nd magnesium alloy

The effects of precipitates on grain size and mechanical properties of as-cast AZ31-x%Nd magnesium alloy were investigated, and the affecting mechanism was also discussed. The results indicated that Al₂Nd phase, Al₁₁Nd₃ phase and a few Al-Mn-Nd-Fe phase were formed when adding 0.38 wt.%–1.46 wt.% Nd into AZ31 melt, coarse Al₂Nd transformed into Al₁₁Nd₃ gradually with the increasing of Nd content. Due to structure and size transformation and content increasing of Al-Nd phase, the grain size of AZ31-x%Nd alloy increased firstly, and then decreased with the increment of Nd content. After reaching a minimum value, once again it rose up, provided that Nd content was further increased. The tensile property reached its optimal value when the adding amount of Nd content was 1.05 wt.%, however, adding excessive amount of Nd deteriorated both ultimate strength and elongation of AZ31 alloy.