稀土对TiAl/Ti3Al界面稳定性和延性影响的第一性原理研究

First Principle Study on the Influence of Rare Earth on Interfacial Stability and Ductility of TiAl/Ti3Al

采用第一性原理计算了La、Ce、Nd、Sm对TiAl/Ti3Al界面形成能、断裂功、弹性性质和电荷布居数的影响。计算结果显示:La、Ce、Nd、Sm占据TiAl/Ti3Al晶界处的形成能比在基体内的要低,更倾向于在晶界处偏聚。Nd掺杂TiAl/Ti3Al断裂功大于纯净界面的,不利于改善界面延性,通过计算弹性模量G/B也得到同样的结论。Mulliken布居和重叠布局显示,Nd掺杂后的共价键强度增强,不利于界面延性改善,而La、Ce、Sm掺杂共价键强度减小,有利于改善界面延性。

By using first principle,the effects of La,Ce,Nd and Sm on the formation energy,work of separation,elastic properties and charge population of TiAl/Ti3Al interface were calculated.The results reveal that formation energy of La,Ce,Nd,Sm occupying the grain boundary of TiAl/Ti3Al is lower than that in the matrix,so they prefer to segregating on the grain boundary.The work of separation of Nd doped TiAl/Ti3Al is greater than that of pure interface,which is not beneficial to improving the interface ductility.The same conclusion is also obtained by calculating elastic modulus G/B.Mulliken population and overlapping population show that Nd can enhance the covalent bond strength,which is not beneficial to the interface ductility,however,La,Ce and Sm will reduce covalent bond strength,which is good for improvement of the interface ductility.