利用第一原理研究合金化对γ-TiAl抗氧化性能的影响

INVESTIGATION ON EFFECTS OF ALLOYING ON OXIDATION RESISTANCE OFγ-TiAl BY USING FIRST PRINCIPLE

利用第一原理平面波赝势方法,计算了含不同过渡族合金原子时Al_2O_3和TiO_2的氧化能,据此分析了合金化对Al_2O_3和TiO_2相对稳定性的影响.计算结果表明,几乎所有合金元素均增加Al_2O_3和TiO_2的氧化能,使其稳定性下降.Al_2O_3和TiO_2氧化能的差值表明,Nb,Mo,W,Re等显著降低Al_2O_3相对于TiO_2的稳定性,因此,可抑制γ-TiAl中Al组分的内氧化,提高γ-TiAl的高温抗氧化性能.

The oxidation energies of A1203 and Ti02 containing different transition metal alloying elements were calculated by using a first-principles plane-wave pseudoptential method, the effect of alloying on the relative stabilities of A1203 and TiO2 was also analyzed. The results showed that almost all the alloying elements increased the oxidation energies of A1203 and Ti02, i.e., destabilized both A1203 and Ti02. Comparing the oxidation energies of A1203 and Ti02, it was foud that, W, Mo, Re, Nb, etc., decreased significantly the stabilities of A1203 relative to that of TiO2, indicating that these alloying elements may hamper efficiently the inner oxidation of A1 in the ^-TiA1 matrix so as to increase the high-temperature oxidation resistance of y-TiA1.