Effects of trace Er addition on the microstructure and mechanical properties of Mg-Zn-Zr alloy

摘要

The effects of trace Er addition on the microstructure in Mg-9Zn-0.6Zr alloy during casting, homogeni-zation, pre-heating, and hot extrusion processes were examined. The mechanical properties of alloys with and without Er were compared. The results showed that Er exhibited a lower solubility in solid magnesium and formed thermally stable Er- and Zn-bearing compounds. The Er-bearing alloy exhibited a considerably improved deformability, as well as a fine and uniform microstructure. Moreover, dynamic precipitation of fine MgZn_2 particles with a modified spherical morphology occurred during hot extrusion, resulting in a tensile yield strength of 313 MPa and a high elongation to failure value of 22%. Further aging of the Er-bearing alloy led to an increment of another 30 MPa in yield strength. In addition, Er markedly increased the thermal stability of the alloy structure.