Ti-Al-Fe体系bcc相扩散系数及原子移动性

Diffusivities and Atomic Mobilities in the bcc Phase of the Ti-Al-Fe System

钛合金中合金元素的扩散行为对材料的制备、加工、服役等过程至关重要。研究了1000和1100℃时Ti-Al-Fe体系bcc相中的元素扩散行为,制备了8对bcc-Ti-Al-Fe单相合金扩散偶。分别在1000℃/8.5 h和1100℃/7 h条件下进行扩散,利用EPMA技术测定成分-距离曲线。通过得到的成分-距离曲线,采用CALPHAD方法建立了Ti-Al-Fe体系bcc相的原子移动性数据库。在优化过程中,采用HitDIC软件得到了原子迁移率参数和互扩散系数。利用得到的原子移动性参数对扩散偶的扩散过程进行了模拟,计算结果与实验扩散特性(互扩散、组分-距离分布和扩散路径)一致,验证了该数据库的准确性。这一研究成果对于深入理解钛合金的微观组织演变和性能具有重要意义。

The diffusion behavior of elements in titanium alloys is crucial to the preparation,processing and service of these materials.In this paper,the diffusion behavior of alloying elements in the bcc phase of a Ti-Al-Fe system at 1000 and 1100℃was studied.Eight pairs of bcc-Ti-Al-Fe single-phase alloy diffusion couples were prepared and annealed at 1000 and 1100℃.The composition-distance profiles of these diffusion couples were determined by using EPMA.An atomic mobility database of the bcc phase in the Ti-Al-Fe system was established by the CALPHAD(calculation of phase diagrams)approach based on the obtained diffusion coefficients.In the optimization process,HitDIC software was used to obtain the atomic mobility parameters and interdiffusion coefficient.Using the obtained atomic mobility parameters,the diffusion processes of the diffusion couples were simulated.The calculated results are consistent with the experimental diffusion characteristics(interdiffusion,composition-distance profiles and diffusion paths),indicating the accuracy of the database.This research is highly important for further understanding the microstructure evolution and properties of titanium alloys.