采用第一性原理计算研究了超硬材料z-BC2N的弹性各向异性性质、应力-应变关系、硬度及最小热导率性质.计算得到的晶体力学行为判据 B/G 为 0.87, 泊松比为 0.084, 普适弹性各向异性指数为 0.09992.[100]晶向上最大拉伸强度达到180 GPa,(100)[010]应变方向上最大剪切强度达到160 GPa,维氏硬度值为77.07 GPa.基于Cahill模型得到的最小热导率为6.811 W/(m·K).结果表明: z-BC2N是脆性材料且力学稳定性良好,有非常高的拉伸强度、剪切强度, 体弹模量为各向同性, 杨氏模量各向异性程度不大.z-BC2N 的最小热导率低于金刚石的最小热导率.
Based on the first-principles calculations, the elastic anisotropic properties, stress-strain relationship, hard-ness and minimum thermal conductivity of the superhard material z-BC2N were investigated. Results show that the Pugh criterionB/G is 0.87, Poisson ratio is 0.084, and the universal elastic anisotropy indexAU equals to 0.09992. The ultimate tensile strength along [100] crystal orientation is up to 180 GPa while the shear intensity of(100)[010]direc-tion peaks at 160 GPa, and 77.07 GPa for the Vickers hardness of z-BC2N. Based on Cahill model the calculated minimum thermal conductivity is 6.811 W/(m·K). Those data indicate that z-BC2N belongs to brittle material with ex-cellent mechanical properties such as the outstanding tensile strength and shear intensity, its bulk modulus is exactly isotropic and the Young's modulus witnesses a significant trend to be isotropic. Besides, z-BC2N possesses a lower minimum thermal conductivity compared with diamond.
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