First Principles Study On Hydrogen Behavior And Mechanical Properties Of TiCrTaV Multi-component Allo

TiCrTaV low activation refractory multi-component alloy is composed of low activation elements,with low thermal neutron absorption cross section and excellent radiation resistance,which is expected to be the structural material of fusion reactor.In this paper,the electronic structures,mechanical properties and hydrogen behaviors of two the BCC phases(BCC1 Ti₂₃Cr₂₅Ta₂₃V₂₉and BCC2 Ti₂₇Cr₂₇Ta₁₈V₂₈)in TiCrTaV multi-component alloys are studied at the atomic level by using first-principles calculations based on density functional theory.（1）Both BCC structures can exist stably.BCC1 structure shows better ductility.BCC2 structure has stronger deformation resistance.There are covalent bonds and metal bonds in both structures.BCC2 structure has strong bond coordination and better thermal stability.The chemical bond formed by Ta atom has covalent bond property.The results show that both VCA and SQS can well predict the lattice constants and mechanical properties of the alloy.SQS method can deeply study the charge transfer and bonding properties between different atoms.VCA method cannot deeply study the electronic structure.（2）The preferential position of hydrogen atom in the two BCC structures cannot be determined from the energy and local lattice distortion.By averaging the dissolution energy and local lattice distortion of hydrogen atoms in different positions,it is found that the tetrahedral interstitial（TI）is slightly better than the octahedral interstitial（OI）.Compared with traditional metal materialsβ-Ti,Ta,V,V-Ti and W,the average solution energies of H in TI of BCC1 and BCC2 are higher,indicating that the two BCC structures of TiCrTaV alloy have certain resistance to the solution of H.The solution energy of H atom is larger,when the Ti atom content in OI is 0.The E^S_bulk≤-0.3 e V,when Ti atom content in OI is 0.5.The E^S_bulk>-0.2e V,when the Ta atom content in TI is 0.5.The E^S_bulk<-0.3 e V,when the Ti atom content in TI is 0.75.The results show that hydrogen atoms in BCC1 and BCC2 are difficult to diffuse over a long distance along the OI-OI and TI-TI diffusion paths in<010>and<110>directions,respectively.（3）The infiltration of hydrogen atom leads to the enhancement of deformation resistance,decrease of toughness and enhancement of bonding strength of covalent bond of the two BCC structures.Hydrogen in TI is more conducive to enhancing the bonding strength.The chemical bond formed by hydrogen atom has the properties of covalent bond and metallic bond...