B掺入CuΣ5晶界间隙位性质的第一性原理研究

The first-principles study on properties of B-doped at interstitial site of CuΣ5 grain boundary

本文采用第一性原理方法对清洁CuΣ5晶界与有B掺杂到间隙位的CuΣ5晶界进行了拉伸和压缩的模拟研究.结果分析表明,CuΣ5晶界结合因B的掺入得到加强.清洁CuΣ5晶界处因有较大空隙而存在电子密度低的区域,晶界结合相对较弱,在拉伸过程中晶界从其界面处开始断裂.有B掺杂在间隙位的CuΣ5晶界电子由Cu向Cu-B间积聚,晶界结合相对较强,拉伸时晶界从其近邻原子层开始断裂.在形变小于20%的压缩过程中,B的掺入未对晶界产生明显影响.

The uniaxial tensile and compression tests of the CuΣ5 grain boundary （GB） with and without segregated interstitial boron have been performed using first principles method based on density functional theory. Results show that boron enhances the cohesion of CuΣ5 GB and improves the mechanical property of Cu significantly. The clean boundary has lower density of valence electrons than perfect lattices and will be the point for fracture to start under sufficiently high tensile stress. The CuΣ5 GB with segregated boron has strengthened the cohesion across the boundary because of the strong B-Cu bond. Charge accumulated to Cu-B decreases slightly the strength of neighboring Cu-Cu bonds, which will be the weak point for fracture to initiate. The ultimate tensile stress is enlarged by the addition of boron. There is no significant effects occurring within 20% of the compression strain due to B-doping.