Effects of Sm and Zr Addition on the Microstructure and Mechanical Properties in Mg-Cu Alloys

The effects of Sm and Zr amount on the properties of Mg-Cu-Sm-Zr alloys were systematically investigated. The results showed that the Mg₉₉Cu alloy consist of-Mg matrix and Mg₂Cu phase. After the addition of Sm and Zr, it was confirmed that Sm and Zr change the structure and distribution of Mg₂Cu phase. In the meantime, the CuZr₂ and CuSm phases which make a major contribution to mechanical properties were observed in the Mg-Cu-Sm-Zr alloys. The addition of Sm and Zr can also greatly refine the grains. The strength continuously increased due to the increase of Sm and Zr content. The elongation first increased within the range of 0-1.5%Sm 0-0.9%Zr, and the decreased. The alloys with 0.5wt%Sm and 1.9wt%Zr had the best combination of mechanical properties.