钛铝合金高温氧化机理电子理论研究

为了从电子层面揭示钛铝合金高温氧化的物理本质,采用递归法与Castep相结合的方式, 计算了原子埋置能、亲和能、结合能等电子结构参数,探索合金氧化机理.研究表明: 氧在钛中有较大固溶度,氧原子可以在钛表面的基体内聚集,逐步向深层扩散. 氧与钛具备较强的亲和力,能形成钛的氧化膜.钛基体中铝原子间具有相互吸引力, 能形成铝的原子团簇.铝原子团簇中的钛原子间相互排斥与铝形成化合物. 铝、钛与氧的亲和能相近,不易发生铝的优先氧化,而是同时生成钛的氧化物和铝的氧化物. Al₂O₃比TiO₂的结合能略低,因而更加稳定,铝在TiO₂中有较大的固溶度, 能替换其中的钛形成更稳定的Al₂O₃氧化物.

The electronic theory study on high-temperature oxidation mechanism of TiAl alloy

In order to reveal the physical nature of high temperature oxidation of titanium-aluminous alloy from the electronic level, the atom embedded energy, affinity energy, binding energy and other electronic structure parameters are calculated by using recursive method combining with Castep, and the alloy oxidation mechanism is explored. The results show that there is a larger oxygen solubility in titanium and oxygen atoms can aggregate into titanium matrix near surface, and gradually spread into the deep matrix. Oxygen and titanium have a strong affinity to form a titanium oxide film. Aluminum can form clusters with mutual attraction between aluminum atoms in titanium matrix. Titanium atoms in aluminum clusters are mutually repulsive and form chemical compounds with aluminum atoms. Because of the closing affinity energy between aluminum and titanium with oxygen, the preferential oxidation of aluminum cannot occur, but titanium oxide and aluminum oxide form. The binding energy of Al₂O₃ is slightly lower than that of TiO₂, therefore Al₂O₃ is more stable. Aluminum in TiO₂ has a greater solubility, which can replace titanium to form more stable oxide Al₂O₃.