First-principles modeling of hardness in transition-metal diborides

作者：Lazar Petr^*; Chen Xing Qiu; Podloucky Raimund

来源：Physical Review B, 2009, 80(1): 012103.

DOI：10.1103/PhysRevB.80.012103

• ab initio calculations
• density functional theory
• dislocations
• elasticity
• fracture
• hafnium compounds
• iridium compounds
• microhardness
• osmium compounds
• rhenium compounds
• shear strength
• stress effects
• tantalum compounds
• tungsten compounds

Based on recent experiments, the diborides OsB2 and ReB2 were proposed to be ultraincompressible and superhard materials. By application of an ab initio density-functional theory approach we investigate the elastic and cleavage fracture properties of the borides MB2 (M= Hf, Ta, W, Re, Os, and Ir). We derive a direct correlation between the lowest calculated critical cleavage stress and the experimental (micro)hardness. By calculating the critical shear stress and estimating the possibility of dislocation emission we can justify the prediction that ReB2 is indeed a superhard material.

• 出版日期2009-7