Effect of Trace Sm Addition on Microstructure and Mechanical Properties of AZ61 Magnesium Alloys

The effect of samarium (Sm) adding (0.0 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt% and 2.0 wt%) on microstructure and mechanical properties of AZ61 magnesium alloys was investigated by OM, XRD, SEM and EDS. The results indicate that volume fraction 0.4%∼2.2% Al2Sm particles with the average diameter of 1∼7 μm are found in AZ61 magnesium alloys with different Sm contents addition. When Sm content increases from 0.0 wt% to 2.0 wt%, the particle size of Al2Sm gradually increases while the content of β-Mg17Al12 decreases. Meanwhile the grain size of AZ61 magnesium alloys after solution treatment at 693 K for 24 h firstly decreases and then increases with Sm content increasing. When Sm content is 1.0 wt%, the grain size is least. The ultimate tensile strength, the yield stress and the elongation of AZ61 magnesium alloys with 1.0 wt% Sm after solution treatment are 215, 142 MPa, and 4.1%, respectively, up to their maximum values.