Investigation Of The Diffusion Properties Of Impurity Atoms In B2-Feal Alloy

Ordered intermetallic FeAl alloy is a kind of new structural materials are widely used with excellent sulfur resistance and antioxidant properties. But the material leads to material failure during processing and loading due to brittle fracture and ductile. A trace amount (ppm) of C and B defects can significantly improve plasticity and abrasion resistance. So it’ s very important to study the diffusion mechanism by theoretical method, and the diffusion mechanism can help to understand the material properties. In this paper, the physical properties and diffusion behaviors of impurities B, C, H point defects in FeAl alloy have been simulated by molecular statics method with EAM potential.Firstly, the lattice constant, cohesive energy, melting point and elastic constants of B2-FeAl have been calculated by EAM potential. The calculated results are good consistent with experimental results and other calculations, which shown that the EAM potential is reasonable.Secondly, the defect formation energy and diffusion mechanism of B, C, H point defects in B2-FeAl have been calculated. The results shown that B easy to occupy on Al site, while C easy to occupy on Fe site, H cann’t informed substitution defects but can occupy on tetrahedral interstice. Interval defectes with the lowest diffusion activation energy among different diffusion mechanisms, and H atom migrate fastest, B atom next, finally is C atom.Thirdly, the surface energy, impurity adsorption energy, and migration energy of (100)-Al, (110) and (111)-Al surface of B2-FeAl have been calculated. The results shown that (110) surface have the lowest energy. Among different adsorption behaviours, H atom has the lowest adsorption energy. It’s mean that H own the strongest adsorption capacity, followed B atoms. Moreover, H atom migrate most easily and spread fastest among impurities, diffusion activation energy of surface and bulk have little different. But B and C migrate at surface faster than in bulk.Finally, we study the property of B, C and H defects and their diffusion mechanisms atΣ:5(310)[001] GB of B2-FeAl. Substitution defects of H unstable and defects information energy of interstice lower than substitution, lowest and exothermic with In2 and In3 site. The lowest diffusion energy of B and C atoms migrate from bulk to boundary is A12 site, and tend to jump with the INN diffusion mechanism.