Lu Cheng, Gong Weiguang, Li Quan, Chen Changfeng
School of Mathematics and Physics, China University of Geosciences (Wuhan), Wuhan 430074, China.
International Center for Computational Method & Software, State Key Lab of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China.
J Phys Chem Lett. 2020 Nov 5;11(21):9165-9170. doi: 10.1021/acs.jpclett.0c02656. Epub 2020 Oct 15.
Transition-metal boron-rich compounds exhibit favorable synthesis conditions and mechanical properties that hold great promise for wide-ranging applications. However, the complex bonding networks of these compounds produce diverse structural and mechanical behaviors that require in-depth studies. A notable case is ZrB, which has been reported to possess high Vickers hardness comparable to those of ReB and WB. Surprisingly, first-principles calculations of stress-strain relations reveal unexpected low indentation strengths of ZrB well below those of ReB and WB. Such contrasting results are reconciled by noting that the additional presence of a boron-rich phase of ZrB in the experimental synthesis process likely plays a key role in the extrinsic strengthening. These findings uncover mechanisms for the higher measured strength of ZrB and offer insights for elucidating extrinsic hardening phenomena that may exist in other transition-metal compounds.
富含硼的过渡金属化合物展现出良好的合成条件和机械性能，在广泛应用方面具有巨大潜力。然而，这些化合物复杂的键合网络产生了多样的结构和机械行为，需要深入研究。一个值得注意的例子是ZrB，据报道它具有与ReB和WB相当的高维氏硬度。令人惊讶的是，应力 - 应变关系的第一性原理计算揭示了ZrB出人意料的低压痕强度，远低于ReB和WB。通过注意到在实验合成过程中ZrB富含硼相的额外存在可能在外在强化中起关键作用，这些相互矛盾的结果得到了调和。这些发现揭示了ZrB更高测量强度的机制，并为阐明其他过渡金属化合物中可能存在的外在硬化现象提供了见解。
