摘要
以密度泛函平面波赝势方法为基础,计算研究了16个La和(或)Zr替代掺杂γ-TiAl体系(S_1,S_2,S_3,S_4,S_(51)~S_(55),S_(61)~S_(65),S_7和S_8)的结构与性质。对平均形成能的计算分析表明,它们均有较好的能量稳定性;根据弹性常量和Born-Huang判据预测,除S_(61)外,15个掺杂体系均具有力学稳定性,预报它们是可以实际制备并稳定存在的。通过对比各体系的弹性模量比,发现La和Zr双掺杂体系的延性(特别是S_(51),S_(52),S_(63)和S_(64))明显改善,且双掺杂体系的延性与杂质原子的相对位置关系不大。布居数、电荷密度分布计算和分析揭示,La和Zr双掺杂γ-TiAl体系各向同性程度提高、延性改善的原因在于体系中Ti 4s→3d,Al 3s→3p电荷转移明显减少、自由电子数量增多,导致p-d轨道杂化作用减弱,Al(La,Zr)-Ti共价键数量减少和Ti-Ti共价键结合强度显著增强,化学键Al-Al,Ti-Ti和Al-Ti的强度明显趋同、金属性增强。
16 La and （or） Zr doped γ-TiAl systems（S1, S2, S3, S4, S（51）-S（55）, S（61）-S（65）, S7 and S8） were constructed and investigated using the plane wave pseudo potentials method based on the density functional theory and other physical theories. The results of average formation energy show that they possess good energy stabilities. According to the elastic parameters and Born-Huang criteria, it is forecasted that they（except system S（61）） are in good mechanical stabilities. So, the 15 doped systems can be prepared in experiment and are stable in existence. The comparison of G/B shows that all La and Zr co-doped systems（especially S51, S52, S63 and S64） have better ductile properties than pure γ-TiAl systems. The ductility of co-doped systems is not much correlated with comparative position of doping atoms. The calculation results and discussion about population, charge densities indicate that the improvements of ductility and isotropy of co-doped systems results from the decrease of Ti 4s→3d, Al 3s→3p charge transfer and increase of free electrons number. This change results in the weakening of p-d orbital hybrid, the decreasing number of bonds Al（La, Zr）-Ti and the increasing strength of covalent bond Ti-Ti, and then the chemical bonds Al-Al, Ti-Ti and Al-Ti distinctly tend towards the same strength and become stronger in metallic property.
作者
宋庆功
赵俊普
顾威风
蒋清杰
杨宝宝
郭艳蕊
胡雪兰
Song Qinggong;Zhao Junpu;Gu Weifeng;Jiang Qingjie;Yang Baobao;Guo Yanrui;Hu Xuelan(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)
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2018年第4期1154-1159,共6页
Rare Metal Materials and Engineering
基金
国家自然科学基金(51201181)
中国民航大学中央高校基本科研业务费(3122014K001)
