Distribution, evolution and the effects of rare earths Ce and Y on the mechanical properties of ZK60 alloys

Eight kinds of Mg-RE alloys were prepared. The distribution, evolution, and effects of RE Ce and Y in the investigated alloys were studied by examining the mechanical properties of Mg alloys using X-ray diffraction and scan electron analysis, and by TEM observation. The results show that among the investigated alloys, ZK60-1.5%Ce and ZK60-1.0%Y possessed the optimal mechanical properties. Ce and Y were distributed on the grain boundary during casting. After extrusion and T5 (150°C/0-24 h) heat-treatment, Ce and Y were distributed along the extrusion direction and they existed in compound form for both as-casting and as-extrusion specimens. The mechanical properties of the investigated alloys were better than those of ZK60 because of the solid solution strengthening of RE and the dispersion strengthening of Mg-RE or Mg-Zn-RE compounds.