相变温度附近等温热处理对Mg97Zn1Y2合金组织演化的影响

Effect of the isothermal heat treatment near the phase transition temperature on microstructrue evolution of Mg97Zn1Y2 alloy

摘要:

研究了相变温度附近等温热处理温度和保温时间对含长周期结构Mg97Zn1Y2合金的组织的影响，并对演变机理进行了探讨。主要研究结论如下：500℃固溶处理时，随着时间的增加，长周期结构有增长的趋势。采用等温热处理可以将Mg97Zn1Y2合金中的枝晶组织转变为球状晶，当合金保温温度范围从540℃~600℃时，组织尺寸由大-小-大的顺序变化，即经过了粗化、分离及球化至最后粗化三个过程。在等温热处理温度为575℃的组织大致演变趋势为：枝晶态-不规则球形+块状-球形状，当保温时间15min，其组织为均匀、圆整的球状晶。

Abstract:

Effects of isothermal heat treatment temperature near the phase transition temperature and holding time on the microstructures of Mg97Zn1Y2 alloys with LPSO structure were studied. Meanwhile, the evolution mechanism was discussed. The main results shows that the long - period structure has a tendency of growing with the increase of time，when the temperature of solid-solution treatment is 500℃. It is found that the dendrite structure of Mg97Zn1Y2 alloy can be transformed into spherical crystal by isothermal heat treatment. When the insulation temperature range of the alloy is from 540℃ to 600℃, the size of microstructures changes in the order of large-small-large, in other words, it is coarsened, separated and spheroidized, and finally coarsened. The trend of microstructure evolution is from dendritic to irregular spherical and massive, and finally spherical at the isothermal heat treatment temperature of 575 ℃. When the holding time is of 15min, its microstructures are rounded spherical crystal.