Mo掺杂对γ-TiAl基合金能量稳定性和抗氧化性的影响  

Effect of Mo Addition on Energy Stability and Oxidation Resistance ofγ-TiAl Based Alloys:a Study Based on First Principles Calculation

作　　者：宋庆功 董珊珊[2] 胡烨 康建海 严慧羽 王明超 刘志锋 SONG Qinggong;DONG Shanshan;HU Ye;KANG Jianhai;YAN Huiyu;WANG Mingchao;LIU Zhifeng(Institute of Low Dimensional Materials and Technology,College of Science,Civil Aviation University of China,Tianjin 300300,China;Sino-European Institute of Aviation Engineering,Civil Aviation University of China,Tianjin 300300,China)

机构地区：[1]中国民航大学理学院,低维材料与技术研究所,天津3003002 [2]中国民航大学中欧航空工程师学院,天津300300

出　　处：《材料导报》2021年第2期2057-2063,共7页Materials Reports

基　　金：国家自然科学基金(51802343)。

摘　　要：γ-TiAl基合金是一类具有广阔应用前景的高温结构材料,改善其高温抗氧化性能是当前研究的热点之一。以第一性原理计算为基础,研究了Mo含量小于9.26%(原子分数)的20种γ-TiAl基合金体系的几何性质、密度、原子平均形成能、间隙O原子的形成能、Al空位和Ti空位的形成能。结果显示:各种Mo替位掺杂γ-TiAl基合金体系的密度升高,但均小于4.5 g·cm-3,仍具有替代传统镍基合金的密度优势。各个掺杂体系的总能量和原子平均形成能均小于零,显示它们具有良好的能量稳定性,据此预测它们可以由实验制备。随Mo含量的升高,掺杂体系的稳定性逐渐降低。通过对Mo掺杂γ-TiAl体系的O原子形成能差值ΔE f(O)、Al空位与Ti空位形成能差值ΔE V的计算和分析揭示,当Mo含量为4.0%~7.4%时,阻碍间隙O原子扩散的势垒增大,Al空位扩散的能力得以提升且Ti空位扩散的能力被抑制。这对在γ-TiAl基体表面生成α-Al 2O 3占主导地位的连续致密氧化膜有重要作用,为研发抗氧化性能优良的新材料提供了理论依据。γ-TiAl based alloy is a kind of high temperature structural materials with wide application field.Improving its high temperature oxidation resis-tance is one of the research hotspots.The geometric properties,densities,average formation energies of atom,formation energies of interstitial oxygen(O)atom,aluminum(Al)vacancy and titanium(Ti)vacancy of 20γ-TiAl based alloys with Mo content less than 9.26%(atomic percentage)were studied based on the first principles calculation.The results indicate that the density of each Mo substitutedγ-TiAl based alloy system increases,but all of them are less than 4.5 g·cm-3,which still has the density advantage of replacing the traditional Ni based alloys.The total energy and the average atomic formation energy of each doped system are all negative,which show the system has good energy stability and can be predicted to be prepared by experiments.The stability of Mo doped system decreases gradually with the increase of dopant content.Through the calculation and analysis of the difference of formation energy of O atom(ΔE f(O))and the difference(ΔE V)of formation energy of Al vacancy and Ti vacancy(ΔE V)in Mo dopedγ-TiAl system,it is revealed that when the Mo content is 4.0%—7.4%,the alloy system doped with Mo can not only increase the height of barrier of O-atom diffusion,but also promote the improvement of Al vacancy diffusion ability and the inhibition of Ti vacancy diffusion ability.It plays an important role in the formation of continuous,compact and adherent oxide scale dominated byα-Al 2O 3 on the surface ofγ-TiAl matrix,and provides a theoretical basis for the development of new materials with excellent oxidation resis-tance.

关 键 词：Γ-TIAL基合金 稳定性 抗氧化性 第一性原理 

分 类 号：TG178[金属学及工艺—金属表面处理]