Al/Ti液/固界面扩散溶解层形成机制及生长规律

Formation Mechanism and Growth Law of Diffusion Solution Zone between Al/Ti Liquid/Solid Interface

采用镶嵌式扩散偶技术制备Al/Ti扩散偶,在Al熔点以上Ti熔点以下进行扩散热处理,研究Al/Ti液/固界面扩散溶解层的组织结构演变、形成机制及生长规律。实验结果表明,热处理后的扩散溶解层为TiAl3颗粒和含少量Ti的铝基固溶体的混合组织;TiAl3相是热处理过程中最先出现也是唯一出现的新生相;扩散溶解层的生长机制和生长方向随热处理时间的延长发生了改变,在热处理开始后一段时间,扩散溶解层的生长受化学反应速度控制,与保温时间呈线性关系,之后,转变为受扩散控制,与保温时间呈抛物线关系,扩散溶解层的生长方向也由Ti基侧转变为Al基侧;扩散溶解层的厚度与热处理温度呈指数关系。

Al/Ti diffusion couples were made by embedded technology and diffusion heat treatment was carried out between the melting point of Al and that of Ti.The microstructure evolution,formation mechanism and growth law of Al/Ti diffusion solution zone were investigated.The results show that the microstructure of the diffusion solution zone after heat treatment is the mixture of TiAl3 and Al solid solution with a few Ti;TiAl3 forms first and is the only new phase during heat treatment.The growth mechanism and direction of the diffusion solution zone change with prolonging of treating time;first,its growth is controlled by reaction regime and the growth direction is to Ti substrate,and the growth rate and holding time have linearity relation;afterwards,its growth mechanism changes to diffusion regime and the growth direction is to Al substrate,and the growth rate and holding time have parabola relation.For certain time,the thickness of diffusion solution zone and the treating temperature have the index relation.