The interfacial reaction between diamond (100) surface and CuNi-based filler alloys containing Cr by first-principles calculations

Abstract

Brazed diamond tools have the advantages of high holding strength for diamond abrasives, superior grinding performance, formability, etc. The elements used commonly in filler alloys such as Cr, Cu, and Ni have an important impact on the interfacial bond strength and diamond thermal damage. In this work, the interactions between Cu, Ni, and Cr of the filler alloy and the diamond (100) surface were investigated using first-principles calculations. The results indicated that the adsorption energy of Cu adsorbed on the diamond (100) surface was low, suggesting that C atoms are extremely difficult to dissolve into Cu-based filler alloys, which makes Cu-based filler alloys less wettable with diamond. While the adsorption energy of Ni adsorbed on the diamond (100) surface was greater, which may form Ni₃C weak carbide. Therefore, Ni-based filler alloys are usually wettable with diamonds. However, Ni₃C of poor stability may decompose C atoms at the interface, which may lead to greater corrosion of diamonds. The adsorption energy of Cr adsorbed on the diamond (100) surface was the highest among Cu, Ni, and Cr, while the co-adsorption of Cr and C can grow into stable carbides. With the extension of time, the carbides can grow to form continuous layers of carbides. The results are generally consistent with the experimental results.