钛合金蜂窝夹层结构钎焊界面的价电子结构分析

Valence electron structure of brazing joint interface for honeycomb sandwich construction in titanium alloy

对TC1钛合金蜂窝夹层结构试件的钎焊界面组织进行观察、分析确定界面生成相的晶体结构,采用EET理论中BLD方法和平均原子模型,计算分析了钎焊界面价电子结构.从原子间结合力的角度分析了钛合金蜂窝夹层结构钎焊界面的价电子结构,探讨了界面结构与力学性能的本质关系.钎焊过程中界面处生成了六方晶体结构TiNi3(Cu,Zr)化合物和体心立方结构Ti(Ni,Zr,Cu)相.从原子间成键角度,最大共价电子数和晶格电子数分别反映了晶体的强度和塑性.TiNi3(Cu,Zr)化合物和Ti(Ni,Zr,Cu)相的最大共价电子数分别为0.055 8和0.303 7,晶格电子分别为0.993 5和1.392 8,而界面处基体的最大共价电子数和晶格电子数分别为0.305 9和1.397 3.因此,与TiNi3(Cu,Zr)化合物相比,Ti(Ni,Zr,Cu)和钛固溶体晶胞不仅具有较高的强度,还具有相对良好的塑性,而TiNi3(Cu,Zr)化合物相的存在和连续分布不利于钎焊界面的强度和塑性.

In this paper,the microstructure and the precipitations in the interface were studied for the honeycomb sandwich construction in titanium alloy. The valence electron structure of the brazing joint interface was calculated by the empirical electron theory( EET) in solid and molecules. The inter-atomic binding force was analyzed and the relationship between it and the microstructure was discussed. The TiN i3( Cu,Zr)-compound with hcp lattice structure and the Ti( Ni,Zr,Cu) solid solution with bcc structure were formed in the welding. The maximum valence electron and maximum crystal electron for the matrix was0. 305 9 and 1. 397 3,which represented the ability of the strength and ductility for the crystal respectively. For the TiN i3( Cu,Zr) compound and the Ti( Ni,Zr,Cu) phase,the maximum valence electron was 0. 055 8 and 0. 303 7 respectively,and the maximum crystal electron was 0. 993 5 and 1. 392 8 respectively. Thus,the ability of the strength and ductility for the Ti( Ni,Zr,Cu) phase and the matrix is better than that of the TiNi3( Cu,Zr)-compound. The discontinuity of the microstructure in the interface is disadvantage for the strength and ductility.