Effect of mole ratio of Y to Zn on phase constituent of Mg-Zn-Zr-Y alloys
(1. College of Materials Science and Engineering, Chongqing University, Chongqing 400030, China;
2. National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400030, China)
2. National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400030, China)
Abstract: The phase constituent evolution of Mg-Zn-Y-Zr alloys with the mole ratio of Y to Zn both in the as-cast and as-annealed states at the Mg-rich corner was investigated by XRD and SEM/EDS analysis and was further explained from the ternary phase diagram calculation. The results show that the formation of the secondary phases in Mg-Zn-Y-Zr alloys firmly depends on the mole ratio of Y to Zn, and X (Mg12YZn)-phase, W (Mg3Y2Zn3)-phase and I (Mg3YZn6)-phase come out in sequence as the ratio of Y to Zn decreases. The mole ratios of Y to Zn with the corresponding phase constituent are suggested quantitatively as follows: the phase constituent is α-Mg + I when the mole ratio of Y to Zn is about 0.164; α-Mg + I +W when the mole ratio of Y to Zn is in the range of 0.164−0.33;α-Mg +W when the mole ratio of Y to Zn is about 0.33; α-Mg +W+X when the mole ratio of Y to Zn is in the range of 0.33−1.32; and α-Mg +X when the mole ratio of Y to Zn is about 1.32. The results also offer a guideline for alloy selection and alloy design in Mg-Zn-Y-Zr system.
Key words: magnesium alloy; Mg-Zn-Zr-Y; mole ratio; phase constituent