La掺杂WC(0001)/Co(111)界面结合强度、稳定性和电子结构的第一性原理研究

摘要/Abstract

摘要： WC/Co硬质合金的界面结合强度取决于其界面性质。本文运用基于密度泛函理论的第一性原理,构建了6种WC(0001)/Co(111)界面模型,在此基础上,从电荷转移、成键方式和价电子分布等角度分析了La掺杂对WC(0001)/Co(111)界面稳定性最弱和界面稳定性最强模型的影响机理。结果表明:在6种界面模型中,稳定性最弱的是W-OT-Co界面,有最大的界面距离、最小的黏附功和最高的界面能,裂纹倾向于出现在界面;稳定性最强的是C-HCP-Co界面,有最小的界面距离、最大的黏附功和最小的界面能,裂纹倾向于出现在基体;当稀土La分别替换W-OT-Co模型Co侧第二层的Co原子,以及C-HCP-Co模型WC侧第二层的W原子时,两个界面距离才会都变小、黏附功都增大,但强化界面效果不同;掺杂稀土La后,W-OT-Co界面的键合方式为弱离子键和金属键的结合,C-HCP-Co界面的键合方式为强共价键、离子键和金属键的结合,界面更稳定;La在稳定堆积构型C-HCP-Co上的最优掺杂位点将显著提高WC/Co硬质合金的界面结合强度。

关键词: 第一性原理, WC/Co界面, La掺杂, 结合强度, 电子结构, 断裂韧性

Abstract: The interfacial bonding strength of WC/Co cemented carbide depends on its interfacial properties. In this paper, based on the first-principle of density functional theory, six kinds of WC(0001)/Co(111) interface models were constructed. On this basis, the influence mechanism of La doping on the weakest interface stability and the strongest interface stability model of WC(0001)/Co(111) was analyzed from the point of view of charge transfer, bonding mode and valence electron distribution. The results show that among the six interface models, the W-OT-Co interface is the weakest, with the maximum interface distance, the minimum adhesion work and the highest interface energy, and the crack tends to appear at the interface, while the C-HCP-Co interface with the strongest stability has the minimum interface distance, the maximum adhesion work and the minimum interface energy, and the crack tends to appear in the matrix. When the rare earth La replaces the Co atom in the second layer of the Co side of the W-OT-Co model and the W atom in the second layer of the WC side of the C-HCP-Co model, the distance between the two interfaces becomes smaller and the adhesion work increases, but the effect of strengthening the interface is different. After doping rare earth La, the bonding mode of W-OT-Co interface is the combination of weak ionic bond and metal bond, while the bonding mode of C-HCP-Co interface is the combination of strong covalent bond, ionic bond and metal bond, which leads to more stable interface. The optimal doping site of La on stable stacking configuration C-HCP-Co will significantly improve the interfacial bonding strength of WC/Co cemented carbide.

Key words: first-principle, WC/Co interface, La doping, bonding strength, electronic structure, fracture toughness

中图分类号:

O469

张好强, 曹幸飞, 吴昱鑫, 张舵, 侯锁霞. La掺杂WC(0001)/Co(111)界面结合强度、稳定性和电子结构的第一性原理研究[J]. 人工晶体学报, 2024, 53(12): 2113-2123.

ZHANG Haoqiang, CAO Xingfei, WU Yuxin, ZHANG Duo, HOU Suoxia. First-Principles Study on the Bonding Strength, Stability and Electronic Structure of La-Doped WC (0001)/Co (111) Interface[J]. JOURNAL OF SYNTHETIC CRYSTALS, 2024, 53(12): 2113-2123.

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