In this paper, we investigate the elastic properties, bond stiffness, hardness and Debye temperatures for hexagonal P6₃/mmc WX₂ (X = B or N). It is observed that these two compounds are stable in mechanics. Both these two have three typical bonds, W-X bonds, X-X and W-W bonds. By investigating the bond stiffness of these three types of bonds, we found that the bulk modulus of WX₂ is mainly determined by W-X and W-W bonds, while the shear modulus is mainly determined by X-X bonds. In addition, using a theoretical model, we evaluate the hardness of these two compounds. Results showed that the Vickers hardness of WN₂ is much lower than that of WB₂. What’s more, by calculating the Debye temperatures, we found the melting point of WN₂ is much lower than WB₂, and the overall chemical bonds in WB₂ are stronger than that of WN₂.

中文翻译：

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WX 2（X = B和N）的弹性，粘结刚度和硬度的理论研究

在本文中，我们研究了六边形P 6 ₃ / mmc WX ₂（X = B或N）的弹性，粘结刚度，硬度和德拜温度。观察到这两种化合物在力学上是稳定的。这两个都有三个典型的键，即WX键，XX和WW键。通过研究这三种类型的键的键刚度，我们发现WX ₂的体积模量主要由WX和WW键决定，而剪切模量主要由XX键决定。此外，使用理论模型，我们评估了这两种化合物的硬度。结果表明，WN ₂的维氏硬度远低于WB ₂的维氏硬度。更重要的是，通过计算德拜温度，我们发现WN的熔点₂比WB低得多₂，和WB整体化学键₂都比WN强₂。