Mg-Li二元合金热处理中α相的表层偏聚现象

Research on the Surface Segregation of α Phase for Cast Mg-Li Alloy in Heat Treatment Process

研究了α相在Mg-Li二元合金热处理过程中的表层偏聚现象。研究结果表明:当升温速度不低于10℃/min、保温温度高于300℃且试样的表面积和封存空气比例大于1/40(mm-1)条件热处理过程中,镁锂二元合金会出现单一α相在表层的偏聚现象;偏聚层厚度变化趋势随着空气含量的增加先增加后减小,当试样的表面积与空气含量达到1/16(mm-1)时,厚度值最大;冷却速度对偏聚层的致密性有影响,冷却速度越快,致密性越好。

The paper researches the surface segregation phenomenon of α phase for Mg-Li alloy in heat treatment process and the factors affecting the segregation thickness.The phenomenon is analyzed from the alloy thermodynamics of the outward diffusion of lithium atoms.The results show that during the heat treatment process,Li atoms will spread to the sample surface and react with atmosphere,so that Li atoms decline to the surface,leading to a single α phase.The air in the enclosed space and the speed of warming up in heat treatment process play a decisive role for segregation thickness.The cooling rate has a certain degree of influence on the densification of α phase as well.