Detailing interfacial reaction layer products between cubic boron nitride and Cu-Sn-Ti active filler metal

In the present study, we offer an in-depth analysis over the microstructure, thickness and product composition of the interfacial reaction layer generated upon CBN/Cu-Sn-Ti active filler metal at 1223 K. Current findings demonstrate that adequate wettability and satisfactory bonding have been achieved via chemical reactions between Ti and N, B. More importantly, we report, for the first time, the formation of a three-layer juxtaposition of reaction products, namely, TiN, TiB2 and TiB, along the diffusion path of Ti. Meanwhile, we determine the average layer thickness to be 1.24 μm. Through deep etching, we unambiguously present morphologies of the newly formed TiN and TiB2, which are columnar and bulky, respectively, and constitute the formation of a high strength metallurgical interfacial bonding layer, and is crucial towards gaining enhanced grinding performance. Finally, we propose a possible reaction sequence and mechanism that govern the nucleation and growth of corresponding crystals.