VALENCE ELECTRON STRUCTURE OF Fe_2B PHASE AND ITS EIGEN-BRITTLENESS
Fe2B相价电子结构及其本质脆性

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.