First-Principles Study on the Bonding Strength,Stability and Electronic Structure of La-Doped WC(0001)/Co(111)Interface
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.
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