关键词: 掺杂γ-TiAl 合金, 延性, 形成能, 轴比, 弹性模量, 重叠布居数

Abstract:

Using the first-principle method based on density functional theory, Mn-doped γ-TiAl alloy systems, of which the concentrations of Mn substituting Ti or Al are 1/54, 1/36, 1/24 and 1/16 respectively, have been investigated with CASTEP aimes at improving its ductility. Meanwhile, the structure, energy, plastic and electronic properties are calculated and analyzed. The average atom formation energy of all the doped systems is negative, indicating the energy stability of each system. The Mn-substituting-Al systems have got a lower formation energy, which shows that the Mn tends to substitute Al. Results of both the axial ratio and elastic modulus show that doping with Mn can improve the ductility of γ-TiAl alloys by substituting Al, with Ti12Al11Mn showing the best ductility. Comparison of the overlap population of Ti12Al11Mn and pure γ-TiAl indicates doping with Mn can weaken the anisotropy of the covalent bonds in γ-TiAl systems, which contributes partly to the ductility improvement of γ-TiAl alloys.

Key words: doped γ-TiAl alloy, ductility, formation energy, axial ratio, elastic modulus, overlap population