First-principle calculations of mechanical properties and electronic structure of WCoB and Cr doped WCoB under high pressure

Abstract

The WCoB ternary borides have been widely used in high pressure conditions with high melting point and oxidation resistance. Cr doping contributes to high ductility and high hardness, so the mechanical properties and electronic structures of W4Co4B4 and W4Co3CrB4 are explored under pressure among 0–200 GPa. The energy analysis indicates all structures are stable below 170 GPa. The mechanical properties and Debye temperature increase with the increment of pressure, which can be attributed to the increment of covalence. Two hardness models are adopted to evaluate the hardness, implying higher hardness under higher pressure. The DOS and PDOS are adopted to study the electronic structure, which indicate that the high pressure contributes to lower hybridization. All structures are para-magnetism, which is revealed by the analysis of spin of electrons.