Effects of Y and Zn on mechanical properties and damping capacity of Mg-Cu-Mn alloy

Optical microscope, X-ray diffractometer, scanning electron microscope, tensile tester and dynamic mechanical analyzer (DMA) were applied to investigate the effects of Y and Zn additions on microstructure, mechanical properties and damping capacity of Mg-3Cu-1Mn (CM31) alloy. The results show that with the increase of Y and Zn contents, the secondary dendrite arm spacing of alloys is reduced; meanwhile, the yield strength is increased. In low strain amplitude, the damping capacity of alloys with Y and Zn addition is lower than that of CM31 alloy. However, in strain amplitude over 5×10−3, the damping capacity of alloy with a trace of Y and Zn addition (1%Y and 2%Zn, mass fraction) increases abnormally with the increase of strain amplitude and is near to that of pure Mg, probably due to the increase of dislocation density caused by the precipitation of secondary phase. The temperature dependence of damping capacity of above alloy was also tested and discussed.