Improved Interfacial Bonding of C-Bn with Ni-Based Binder Alloys: Fast Searching of Alloying Elements Based on First Principles

Abstract

c-BN based cermet has superior performance while the poor bonding between the c-BN and Ni binder weakened the performance of c-BN/Ni composites. Alloying the Ni binder was an effective method to enhance the bonding of c-BN with binders. However, the normal selection of alloying elements was based on the typical "trial-and-error" experimental method, which has the disadvantages of time-consuming and high cost. Herein, we developed a fast searching method of alloying elements based on first principles, and massive alloying elements, such as Cr, Ti, Al, Si, Zr, Fe, and Co were evaluated to improve the bonding of c-BN with Ni-based binder alloys. Six c-BN/Ni interface models were built considering different termination and interface stacking sequences, and the calculation results showed that the B-top interface had the highest thermodynamic stability and the strongest interfacial bonding strength. Correspondingly, the alloying elements were introduced at the B-top interface and the doping positions were discussed. Combining the results of thermodynamics and electronic structure, it was found that the alloying of Zr and Ti elements can significantly improve interfacial wettability and bonding via forming reactive interfaces. By comparison, the interface bonding enhancement of other alloying elements was little due to the formation of non-reactive interfaces.

Keywords: First-principles calculations, c-BN/Ni interface, Alloying strengthening, Adhesion properties