Abstract:AZ91 magnesium alloy was adopted as master alloy and rare earths (RE) of 1%, 2% and 3% additions were added, respectively. The influence of RE on the microstructure was investigated. By casting fluidity spiral specimens, effect of RE on fluidity was achieved. The microhardness of the alloys was tested. By casting specimens in permanent mold, tensile properties of the alloys with different RE addition at ambient and elevated temperatures were studied. The fracture mechanisms of the alloys were studied by SEM. RE additions cause the formation of Al11RE3precipitation besides phase change in the alloys. RE firstly decreases and then increases the fluidity. RE has little influence on ambient temperature tensile properties but greatly improves high temperature tensile properties at 150℃. Tensile failure of the alloys are mainly brittle cleavage and/or quasi-cleavage fracture.

Key words: rare earth alloys; tensile property; fractures