Ni对Fe_3Si化合物硬度影响的微观组织结构和电子结构研究

采用实验和第一性原理方法,从微观组织结构、电子结构、力学常数和布局分析研究了Ni浓度和烧结温度对Fe_3Si化合物硬度的影响.结果表明Ni含量为3.125at.%时,化合物具有最小硬度值.进一步增加Ni浓度,其硬度增大,B/c44比值先增加后减小,而G/B比值先减小后增加.但当浓度超过6.25at.%后,不仅不能改善Fe_3Si脆性,反而使合金脆化程度加剧,说明适当添加Ni可韧化Fe_3Si化合物.烧结温度较低时,电子结构对Fe_3Si化合物硬度的影响占主导作用,随烧结温度的升高,先析出的晶粒迅速长大,Ni含量对化合物硬度的影响有所减弱,微观组织结构的影响大于电子结构.

Study of microstructures and electronic structures for effect of Ni concentration on Fe3Si compounds

An experimental set-up was designed according to the microstructure, the electronic structure, the mechanical constants and population analysis. The influences of Ni content and sintering temperature on the hardness of Fe3Si intermetallic compounds have been studied by the experiment and first principles. The research results show that the compound has the lowest hardness with a Ni content of 3.125at.%. Then with further increase of the concentration of Ni, the hardness of compound increases gradually, the value of B/c44 increases firstly and then decreases, and the value of G/B increases firstly and decreases later. When the concentration of Ni more than 6.25at.%, not only cannot have improve the brittleness, instead will play a negative influence, which indicate that the appropriate Ni could toughen the Fe3Si compound. The effect of electronic structure on Fe3Si compound is in leading side in lower sintering temperature. The grain size of pre-nucleated Fe3Si phase rises with the increasing of sintering temperature and the influence of Ni element is weak, but the influence of microstructure strengthens gradually.