Effects of Gd/Y Ratio on the Microstructures and Mechanical Properties of Cast Mg–Gd–Y–Zr Alloys
Three Mg–xGd–yY–0.5Zr (x + y=13, wt%) alloys were prepared by sand casting to investigate the effects of Gd/Y ratio on the microstructures and mechanical properties. The results show that Gd/Y ratio had little influence on the grain size and the phase constitution of the microstructures. However, the volume fraction of the second phase Mg24(Gd, Y)5 in as-cast state increased, while that of the cubic phase (Y, Gd)H2 in as-solutionized state almost unchanged with the decrease of Gd/Y ratio. The uniaxial tension tests of the three alloys show that for both as-solutionized and as-aged states, the yield strength was slightly increased but the ductility was apparently decreased with the decrease of Gd/Y ratio from 3.33 to 1.17. It was thought that Gd and Y atoms in Mg matrix have approximate solute strengthening effect but different adverse effect on ductility, which should be responsible for the mechanical properties difference for the three alloys.
KeywordsCast Mg–Gd–Y alloy Gd/Y ratio Microstructure Mechanical properties
This work was funded by the National Key Research and Development Program of China through Project No. 2016YFB0301104, the National Natural Science Foundation of China (NSFC) through Projects No. 51531002, No. 51301173, No. 51601193 and No. 51701218, the National Science and Technology Major Project of China through Project No. 2017ZX04014001, and the National Basic Research Program of China (973 Program) through Project No. 2013CB632202.
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