Fe_2B相价电子结构及其本质脆性

VALENCE ELECTRON STRUCTURE OF Fe_2B PHASE AND ITS EIGEN-BRITTLENESS

根据固体与分子经验电子理论对Ｆｅ_２Ｂ相的价电子结构进行了定量分析，通过键距差（ＢｏｎｄＬｅｎｇｔｈＤｉｆｆｅｒｅｎｃｅ）方法计算了Ｆｅ_２Ｂ晶体配位团各键上的共价电子数。结果表明，沿［２２０］位向分布的Ｆｅ－Ｆｅ原子键最强，其共价电子数ｎ_Ａ＝０．３８５２，键能Ｅ_Ａ＝１５．７３７２ｋＪ／ｍｏｌ；沿［００２］位向分布的Ｂ－Ｂ原子键较弱，其共价电子数ｎ_Ｄ＝０．１３９２，键能Ｅ_Ｄ＝４．５０５２ｋＪ／ｍｏｌ。从而建立了Ｆｅ_２Ｂ晶体原子间的空间键络，并从键络分布的不均匀性解释了Ｆｅ２Ｂ本质脆性的产生原因。将Ｆｅ_２Ｂ脆性的实验观察和理论分析结果相比较。

The valence electron structure of Fe_2B phase was studied on the basis of Yu's empirical electron theory of solids and molecules.The values of valence electrons on every bond in an atomic coordinate cluster were calculated by the method of bond length difference(BLD). The results showed that the bonds between Fe-Fe atoms along (220] direction were strongest, of which the value of valence electrons n_A=0.3852 and the bond energy E_A = 1 5.7372 kJ / mol, The bonds between B-B atoms along [002] direction were weaker, of which n_D = 0. 1 392 and E_D = 4.5052 kJ/ mol. A space bond network of Fe_2B crystal was built,so the cause of the eigen-brittleness could be translated by a heterogeneity of the bond distribution. Comparing experimental results to theoretical analysis, it came to the conclusion that there was a conformability between them.