Effect of Al addition on microstructure and mechanical properties of as-cast Mg-4Y-3Nd alloy

The microstructure and mechanical properties of Mg-4Y-3Nd-xAl (x = 0, 0.6, 0.9, 1.2, 1.5, 2.0%) alloys were investigated in the present work. The results show that the addition of Al can refine the grain of as-cast Mg-4Y-3Nd alloy significantly. The refining effect increases first and then decreases with increasing Al addition. The grain size of Mg-4Y-3Nd alloy is smallest when the Al addition is 1.5%. The reason for refinement is that the in-situ Al2RE particles reacted Al with RE can serve as for alpha-Mg matrix. The orientation relationship between Al2RE particles and alpha-Mg was determined by TEM analysis: . The effective size of Al2RE particle served as heterogeneous nucleation site is 1 similar to 12 mu m. In addition, the strength and ductility of the alloy increase with the increase of Al addition. The Mg-4Y-3Nd-Al alloy with the higher mechanical properties can be attributed to fine grain strengthening and second phase strengthening.