paper

Metal deficient AlB $_{2}$ -type (Ti $_{0.2}$ Zr $_{0.2}$ Hf $_{0.2}$ Nb $_{0.2}$ Ta $_{0.2}$ ) $_{1 - I^´}$ B $_{2}$ high-entropy diborides with high hardness

arXiv:2302.07418 · doi:10.1016/j.ceramint.2022.11.100

Abstract

We report the synthesis and characterization of metal deficient (Ti $_{0.2}$ Zr $_{0.2}$ Hf $_{0.2}$ Nb $_{0.2}$ Ta $_{0.2}$ ) $_{1 - I^´}$ B $_{2}$ high-entropy diborides (HEBs). A single homogeneous AlB $_{2}$ -type phase is successfully obtained over the $I^´$ range of 0.03 $\leq$ $I^´$ $\leq$ 0.18. With increasing $I^´$ , the unit-cell volume exhibits a nonmonotonic variation with a maximum at $I^´$ = 0.07. These metal-deficient HEBs possess high Vickers hardness of 16.6-18.9 GPa at a load of 9.8 N and their phase stability is attributed to the increased mixing entropy. Our results not only present the first series of metal-deficient AlB $_{2}$ -type HEBs, but also suggest the existence of similar multicomponent diborides.

7 pages, 4 figures

Metal deficient AlB2​-type (Ti0.2​Zr0.2​Hf0.2​Nb0.2​Ta0.2​)1−I^´​B2​ high-entropy diborides with high hardness

Abstract

Metal deficient AlB $_{2}$ -type (Ti $_{0.2}$ Zr $_{0.2}$ Hf $_{0.2}$ Nb $_{0.2}$ Ta $_{0.2}$ ) $_{1 - I^´}$ B $_{2}$ high-entropy diborides with high hardness