Ti-Al-Cr体系高温BCC相扩散及原子移动性

Diffusion and atomic mobility of high temperature BCC phase in Ti-Al-Cr system

针对钛及其合金的扩散研究有助于预测钛合金在热处理过程中的相组成及微观结构的演变。本文采用扩散偶法研究Ti-Al-Cr三元系BCC相中的扩散行为,制备的一系列扩散偶分别在1373 K和1473 K下退火8 h。通过EPMA获得成分-距离曲线,并使用ERFEX函数拟合。利用Whittle-Green和Hall方法获得互扩散系数和杂质扩散系数,发现在Ti-Al-Cr体系BCC相中Al原子的扩散明显比Cr原子快,同时Al原子的主扩散系数和杂质扩散系数均随Al和Cr浓度升高而增大,Cr则正好相反。使用实验测得的扩散系数评估原子移动性,建立Ti-Al-Cr体系BCC相的原子移动性数据库,通过DICTRA软件模拟得到的成分-距离曲线、扩散通道和主扩散系数的计算值与实验结果的对比吻合性较好,验证了数据库的准确性。

The diffusion study of titanium and its alloys can benefit to predict the phase constitution and microstructure evolution of titanium alloys during heat treatment.In this work,the diffusion behavior in BCC phase of Ti-Al-Cr ternary system was studied through diffusion couples method,a series of diffusion couples which was prepared and annealed separately at 1373 K and 1473 K for 8 h.The composition-distance profile measured via EPMA was fitted by ERFEX function.The inter-diffusion coefficients and impurity diffusion coefficients were extracted by Whittle-Green method and Hall method.It was found that the diffusion rate of Al in BCC phase of Ti-Al-Cr system is much faster than Cr.Meanwhile main diffusion coefficients and impurity diffusion coefficients of Al increase as the concentration of Al and Cr increase,which is contrary for Cr.The diffusion coefficients measured in experiments were used to assess the atomic mobility and develop the atomic mobility database of the BCC phase in the Ti-Al-Cr system.The comparison between the simulated results(including composition-distance profiles,diffusion paths and main diffusion coefficients)and the experimental data showed a good consistency,which verify the accuracy of the database.