First-principles modeling of hardness in transition-metal diborides

Petr Lazar, Xing-Qiu Chen, Raimund Podloucky
2009 Physical Review B  
Based on recent experiments, the diborides OsB 2 and ReB 2 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 MB 2 ͑M = Hf, Ta, W, Re, Os, and Ir͒. We derive a direct correlation between the lowest calculated critical cleavage stress and the experimental ͑micro͒hardness. By calculating the critical shear stress and estimating the possibility
more » ... f dislocation emission we can justify the prediction that ReB 2 is indeed a superhard material.
doi:10.1103/physrevb.80.012103 fatcat:ame7znprb5aqphonx2wy2qgluq