【摘要】 采用基于密度泛函理论的第一性原理方法，建立了稀土La在TiAl₃相择优生长面（001）吸附的9种La/TiAl₃（001）表面模型和La空位吸附前后TiAl₃（001）表面堆垛生长表面模型，以此为基础计算并对比了Al-5Ti-1B中间合金中加入La前后TiAl₃（001）表面模型的吸附能、表面能和态密度等。同时计算了La吸附前后TiAl₃（001）堆垛生长后表面模型的表面能，探讨了Al-5Ti-1B-0.6La中间合金中La对细化相TiAl₃生长的影响和作用方式。结果表明，La在TiAl₃（001）表面的9个吸附位置均能自主发生强化学表面吸附，其中Al-TiAl₃（001）表面空位（V₂）吸附La后表面能降低幅度最大，吸附能最小，吸附结构最稳定；TiAl₃（001）表面空位吸附（V₂）La后堆垛生长是趋于单位面积内表面能增加，La吸附后的TiAl₃（001）表面堆垛生长不稳定，减缓了TiAl₃（001）面的生长速度，说明La对TiAl₃相的生长有较强的抑制作用。试验表明，La加入Al-5Ti-1B中间合金后，细化相TiAl₃的平均尺寸由26.47μm降低到14.52μm, TiAl₃相分布较均匀，说明La的加入有利于抑制TiAl₃的长大，与模拟结果一致。更多还原

【Abstract】 9 kinds of La/TiAl₃（001） surface configurations adsorbed by La on the preferred growth surface of TiAl₃（001） and stacking growth configuration of TiAl₃（001） surface before and after La vacancy adsorption were established based on DFT and first-principle method. On this basis, the adsorption energy, surface energy and state density of TiAl₃（001） surface configuration in the Al-5Ti-1B-0.6La master alloy before and after La addition were calculated comparatively. Meanwhile, the effects of La on the growth of the refined TiAl₃ phase as well as the action method were explored. The results indicate that La can spontaneously undergo strong chemical surface adsorption on the nine adsorption sites of the TiAl₃（001） surface, where the surface energy of Al-TiAl₃（001） surface vacancies（V₂） site after adsorbing La has the largest reduction, and the adsorption energy has the smallest reduction, with the most stable adsorption structure. The stacking growth of TiAl₃（001） after La adsorption on the surface vacancies（V₂） site tends to an increase of surface energy and unstable, which retards the growth of TiAl₃（001） surface, indicating that La strongly inhibits the growth of TiAl₃ phase. The test reveals that after adding La to the Al-5Ti-1B master alloy, the average size of the refined TiAl₃phase is decreased from 26.47 to 14.52 μm, with relatively uniform distribution, proving that La addition is beneficial to hinder the growth of TiAl₃, which is consistent with the simulated ones.更多还原