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利用离散变分Xa法计算了单晶Ni_3Al的一个原子簇(Ni_(15)Al_(12)),并据此分析了能级结构、电子态密度,计算了Ni_3Al中原子间的键级及相应的组成。键组成分析证明:Ni-Al键与Ni-Ni键具有较好的相似性,p-d键在两种键的组成中都占有较大比例。Ni_3Al的Ll_2结构,使两种相似的键在空间呈均匀分布,宏观上Ni_3Al表现出较高的强度。单晶体良好的韧性归因于Ni-Al键与Ni-Ni键的相似性,方向性较强的共价键在晶界处受到削弱导致多晶体的本征脆性。
An atomic cluster (Ni_ (15) Al_ (12)) of single crystal Ni_3Al was calculated by the discrete variational Xa method. Based on this, the energy level structure and electronic density of states were calculated, and the bond order of the atoms in Ni_3Al The composition. Bond composition analysis shows that Ni-Al bond has good similarity with Ni-Ni bond, and p-d bond occupies a large proportion in the composition of both bonds. Ni_3Al Ll_2 structure, so that two similar bonds were evenly distributed in space, macroscopically Ni_3Al showed higher intensity. The good toughness of the single crystal is due to the similarity of the Ni-Al bonds to the Ni-Ni bonds, and the more directional covalent bonds are weakened at the grain boundaries resulting in the intrinsic fragility of the polycrystalline body.