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计算了TiB与TiB2的价电子结构,研究了TiB、TiB2的价电子结构与TC4合金渗硼层硬化的关系。研究发现:TC4合金渗硼层的TiB2和TiB相中B-B原子键合力最强,且远大于合金基体组成原子的键合力;TiB2相最强共价键的共价电子对数nTiB2为A 0.5554,TiB相最强共价键的共价电子对数nTiB A为0.4042,因此TiB2相对基体的硬化作用更强;TiB2相的原子状态组数σN为123,而TiB相的原子状态组数σN为19,所以TiB2相的稳定性更高;由相成键能力F的计算可知,从热力学角度看,渗层中TiB应比TiB2多;共价键空间分布决定了TiB晶体易沿[010]晶向生长成短纤维状,而TiB2相易于生成高对称性的粒状或球状,故TiB2比TiB更有利于硬化基体。
The valence electron structures of TiB and TiB2 were calculated and the relationship between the valence electron structures of TiB and TiB2 and the hardening of boronizing layer of TC4 alloy was studied. It is found that the bond strength of BB atom in TiB2 and TiB phase of TC4 alloy is the strongest and much larger than that of alloy matrix. The covalent electron logarithm (nTiB2) of the strongest covalent bond in TiB2 phase is 0.5554, TiB phase covalent bond covalent electron pair nTiB A is 0.4042, TiB2 relative to the matrix hardening stronger; TiB2 phase group number of atoms σN is 123, and TiB phase group number of atoms σN 19 , The stability of TiB2 phase is higher. From the calculation of phase-bonding ability F, TiB should be more than TiB2 in the infiltrated layer from the thermodynamic point of view. The covalent bond spatial distribution determines that the TiB crystal is easy to follow the [010] crystal orientation Grow into short fibers, and TiB2 phase easy to generate high symmetry of granular or spherical, so TiB2 TiB more conducive to hardening of the matrix.