Nb掺杂对γ-TiAl抗氧化能力影响的第一性原理研究  

Influence of Nb doping on oxidation resistance of γ-TiAl:A first principles study

作　　者：李虹[1] 王绍青[1] 叶恒强[1] 

机构地区：[1]中国科学院金属研究所,沈阳材料科学国家(联合)实验室,沈阳110016

出　　处：《物理学报》2009年第F06期224-229,共6页Acta Physica Sinica

基　　金：国家重点基础研究发展计划(批准号:2006CB605103)资助的课题~~

摘　　要：添加Nb被证实是提高TiAl合金抗氧化能力最有效的途径之一,但对于其机理仍然存在一些相互矛盾的解释.运用第一性原理方法对γ-TiAl氧化过程中存在的几种重要点缺陷杂质进行了系统的研究.在确定杂质的稳定结构基础之上,研究发现:γ-TiAl中Nb掺杂的形成能随着含量的增加而升高,导致γ-TiAl相的稳定性降低,对抗氧化性能造成不利影响;而间隙O和Ti空位的形成能随Nb掺杂量的增加而显著升高,因此Nb能有效地降低氧扩散及空位缺陷的进入,从而提高γ-TiAl的抗氧化性能;Nb掺杂对降低杂质含量的作用存在明显的局域特性,是一种近程作用,因此Nb在γ-TiAl中的作用与其含量和分布有关.Nb doping is proved to be the most promising way of enhancing the oxidation resistance of TiAl alloys, yet the intrinsic mechanism is still unclear. To understand the effect of Nb doping, a first principles study of several point defects in γ-TiAl during oxidation is performed. Besides the determination of the stable defect structures it is revealed that （ 1 ） the formation energy of Nb doping increases with Nb content increasing, at the cost of degradation of the phase stability, which is a hindrance to the oxidation resistance; （2） the abilities of interstitial oxygen and titanium vacancy formation are lowered by Nb addition, thus oxygen diffusion and vacancy formation are reduced correspondingly, which enhances the oxidation resistance of the alloy; （3） the effect of Nb doping on the formation energy of point defect is rather localized, therefore the influence of Nb doping is correlated with its distribution and content in γ-TiAl.

关 键 词：Γ-TIAL 高温氧化 Nb掺杂 形成能 

分 类 号：O483[理学—固体物理]