Pan Yong, Chen Shuang, Jia Yanlin
School of Materials Science and Engineering, Southwest Petroleum University Chengdu 610500 China
College of Materials Science and Engineering, Central South University Changsha 410083 China
RSC Adv. 2019 Oct 18;9(58):33625-33632. doi: 10.1039/c9ra07702b.
Although HfB is a promising surperhard material because of the boron cuboctahedron cage, the Vickers hardness of HfB remains controversial. We apply first-principles calculations to investigate the influence of a transition metal on the structural stability, Vickers hardness and thermodynamic properties of HfB. The Vickers hardness of HfB is 39.3 GPa. In particular, the Vickers hardness of TM-doped HfB, which are novel superhard materials, is larger than 40 GPa. The Vickers hardness of Re-doped HfB is up to 47.6 GPa. The improvement of Vickers hardness is that the introduction of an alloying element improves the localized hybridization between B and Hf, and then enhances the bond strength of the B-B covalent bond and the Hf-B bond. In addition, these alloying elements enhance the melting-point and Debye temperature of the HfB. Therefore, we believe that alloying is an effective method to improve the Vickers hardness and thermodynamic properties of HfB superhard material.
尽管由于硼立方八面体笼结构，HfB是一种很有前景的超硬材料，但HfB的维氏硬度仍存在争议。我们应用第一性原理计算来研究过渡金属对HfB的结构稳定性、维氏硬度和热力学性质的影响。HfB的维氏硬度为39.3吉帕。特别地，作为新型超硬材料的过渡金属掺杂HfB的维氏硬度大于40吉帕。Re掺杂HfB的维氏硬度高达47.6吉帕。维氏硬度的提高是因为合金元素的引入改善了B和Hf之间的局域杂化，进而增强了B-B共价键和Hf-B键的键强。此外，这些合金元素提高了HfB的熔点和德拜温度。因此，我们认为合金化是提高HfB超硬材料维氏硬度和热力学性质的有效方法。
