第一性原理研究FeAl金属间化合物脆性

Study on the Brittleness of FeAl Intermetallic compounds by First Principle

为了研究FeAl金属间化合物的脆性,采用第一性原理计算方法,建立了FeAl超晶胞模型,对H原子掺杂前后的FeAl的电子结构进行计算。计算结果显示:在B2型金属间化合物FeAl中,Al原子的sp杂化轨道具有较强的方向性,参与形成的FeAl之间pd极化键导致了晶体的脆性。在H原子掺杂浓度为1.82%的情况下,FeAl体系中置入H原子,与H原子近邻的Al原子状态发生改变,更多的晶格电子为了与H原子成键,转化为共价电子,使晶体内局域金属性下降。由于H原子参与成键,晶体内形成具有明显各向异性的键络,更易于解理。

In order to study the brittleness of the FeAl intermetallic compounds, the first-principle calculation is adopted, a supercell FeAl model is establishing for calculating the electronic structure of FeAl before and after doping H atom. The calculation results show that： in the B2 type FeAl intermetallic compounds, the sp hybrid orbital of Al atoms has a strong directivity and the pd polarization bond participating in the formation of FeAl causes the brittleness of the crystal. When the doping concentration of H atoms is 1.82%, the H atoms is put into the FeAl system and then the state of Al atom will change which is near H atoms; more lattice electrons translate into shared electron to bond with H atoms, and make the metallicity descend at part of the crystal. Since the H atoms participate in the bonding, the bond network with obvious anisotropy forms in the crystal, which makes the cleavage be more easily.