Phases equilibrated with long-period stacking ordered phases in the Mg-rich corner of the Mg-Y-Zn system

摘要

Phase equilibria involving the long-period stacking ordered phases including 14 H,18 R and 10 H in the Mg-rich corner of the Mg-Y-Zn system at 400 and 500℃ have been experimentally investigated by using X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM)and high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM).The coexistence of 14 H and 18 R as well as 18 R and 10 H was confirmed from atomic scales.The phases 14 H,18 R and 10 H were all stable phases from 400 to 500℃.The experimentally proved three-phase equilibrium of14 H,18 R and α-Mg instead of 14 H,18 R and Mg_(24)Y_(5) were presented in the modified isothermal sections.The latter three-phase equilibrium was reported in the available literature.The modified isothe rmal sections are conducive to guide the composition design to obtain the alloys with favorable microstructure constituents and mechanical properties.