Mechanism of Mn in controlling the microscopic characterization and interfacial properties of CuSnTiGa filler metal for brazing diamond abrasives

Improving the bond strength between Cu-based brazing material and diamond abrasive grits has been a hot research topic in the manufacturing field. In this experiment, Mn was added to CuSnTiGa filler metal to obtain diamond tools with high bond strength and high grinding efficiency. Using scanning electron microscopy and energy spectroscopy, it was found that with the increase of Mn element in the CuSnTiGa filler metal, the supercooling of the filler metal increased, the Sn3Ti5 phase became fine, and the content of eutectic tissue increased. On the contrary, the thickness of the TiC layer at the brazed diamond interface decreases with the addition of Mn elements, while the bias of Ti and Sn elements at the interface moves away from the diamond. The addition of 4 wt% Mn results in the smoothest diamond grit-to-filler metal joints with the least porosity. The results of first-principles calculations further validate that manganese reduces titanium-catalyzed diamond graphitization, which in turn reduces the thickness of the TiC layer and the bias of titanium at the interface. In addition, samples prepared with a manganese addition of 4 wt% showed the best grinding efficiency and the highest lifetime. Our work presents a method to improve the grinding performance as well as the service life study of diamond tools: the thickness of the TiC layer and the microstructure distribution at the interface between diamond grits and filler metal were modulated by the addition of Mn.