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

Abstract

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.