采用密度泛函理论(DFT)计算方法,分别考察了高压(0~40 GPa)下D022四方晶格和L12立方晶格Al3Ti的形成能和相稳定性。采用三种交换关联泛函,对优化后的平衡结构及其形成能进行计算,计算结果表明：在0 GPa下D022-Al3 Ti的形成能小于L12-Al3 Ti,即常压下D022晶格结构在热力学上更加稳定；然而,随着外压升高, L12和D022晶格之间形成能的差值不断降低,当压强高于20~30 GPa后, L12-Al3 Ti的形成能反而小于D022-Al3 Ti的形成能,这说明在高压下(>20~30 GPa), L12晶格结构反而在热力学上更加稳定。据此可知,当压强升高至20~30 GPa时, Al3 Ti将发生从D022晶格转变为L12晶格的高压相变。%Phase stability, elastic and thermodynamic properties, and electronic structure of titanium trialuminide ( Al3 Ti) with L12 and D022 structures under pressure up to 40 GPa were investigated using density functional theory ( DFT) calculations. By using three different exchange and correlation potentials, the equilibrium structure was obtained after geometry optimization, and formation energies were calculated. The results showed that the formation energy of D022-Al3 Ti was more negative than the value of L12-Al3 Ti, which meant the phase structure of D022 was more stable in thermodynamics under normal pressure. However, the difference between the formation energies of L12- and D022-Al3 Ti decreased with pressure increasing. The formation energies of L12-Al3 Ti became smaller than the values of D022-Al3 Ti under pressures above 20~30 GPa, which indicated the L12 became more stable in thermodynamics at higher pressures (>20 ~30 GPa ) . Summarily, high pressure induced transition of Al3 Ti from D022 structure into L12 structure was predicted when pressure increased to about 20~30 GPa.
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