Effects of Ho content on microstructures and mechanical properties of Mg-Ho-Zn alloys

Abstract In this work, the microstructures and mechanical properties of as-cast Mg-xHo-2Zn ( x  = 4, 6 and 8 wt%) alloys have been studied by using optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and tensile test at different temperatures. The Ho element exhibits an influence on the grain refinement of the alloys. Increasing Ho content promotes the formation of long period stacking ordered (LPSO) structure, which changes the mechanical properties of the alloys. As a consequence, the strength of the alloy rises with the increase of Ho addition at room temperature and elevated temperature. However, the elongation of the alloy increases at room temperature but slightly decreases at high temperature when the Ho addition increases. These results are explained from morphology evolution of W-phase and the presence of LPSO phase in different alloys.