Mn在γ′-Ni_(3)Al中的择优占位

Preferential occupation of Mn inγ′-Ni_(3)Al

用3种方法探究Mn在γ′-Ni_(3)Al中的择优占位情况。位置优先能的计算结果显示Mn在Ni_(3)Al中有强烈占据Ni亚晶格的倾向。转移能的计算结果显示Mn仍然占据Ni亚晶格,但是占据倾向较弱。第一性原理结合Wagner-Schottky模型的计算结果表明,0 K时,Mn在Ni_(3)Al中无明显占据倾向,随着温度的升高,在富Al的Ni_(3)Al合金中,Mn由占据Ni亚晶格转为占据Al亚晶格;在正常化学计量比的合金中,Mn由无明显占据倾向转变为占据Al亚晶格;在富Ni的合金中,Mn一直占据Al亚晶格。显然利用Wagner-Schottky模型可得到与实验结果相符的结论,同时可考察掺杂原子在γ′-Ni_(3)Al中的占位随合金成分及温度的变化。

In this paper,three methods are used to explore the preferential site occupation of Mn inγ′-Ni_(3)Al.According to the calculated results of site preference energy,Mn has a strong tendency to occupy the Ni sublattice in Ni_(3)Al alloys.The calculated results of transfer energy show that Mn atoms have a weak tendency to occupy the Ni sublattice.By using the Wagner-Schottky model,it is shown that Mn has no site preference in stoichiometric Ni_(3)Al at 0 K.With the increase of temperature,the site preference of Mn changes from occupying the Ni sublattice to the Al sublattice in Al-rich Ni_(3)Al alloys.For stoichiometric alloys,the site preference of Mn changes from no obvious tendency to the Al sublattice.Mn will occupy the Al sublattice in Ni-rich alloys.Accordingly,the change of the site preference of doping atoms with the alloy composition and temperature in Ni_(3)Al alloys can also be investigated using this model.