Exploring the role of indium on the microstructure evolution and interface bonding behavior of brazing diamond abrasive with modified Cu–Sn–Ti

In the brazed joints prepared by Cu-Sn-Ti filler metal, it was found that the filler metal has poor wettability to diamond and diamond abrasive grits are prone to uneven wear resulting in low efficiency of diamond tools and difficulty in achieving the expected processing which are the key factors restricting the performance of brazed diamond tools with Cu based filler. This study aims to improve the wettability of Cu-Sn-Ti filler metal and the brazed joint wear resistance. For this purpose, a new Cu-Sn-Ti-Ga-In composite filler metal was proposed. In this experiment, the subcooling degree and microstructure morphology of the new filler metal were investigated, the microhardness and shear strength of the filler metal were determined, and the shear fracture morphology was analyzed. Wetting tests were conducted on graphite plates to study the effect of indium elements on the wettability of the filler metals. Brazed joints were also prepared, and the crawling morphology of the filler metal on the diamond surface and the wear marks of the diamond abrasive after the frictional wear test were observed. The test results show that Sn3Ti5 is a solid solution is favorable to explain some phenomena. The indium element can increase the subcooling of the filler metal, thus promoting the refinement of Sn3Ti5, and the formation of eutectic microstructure. In brazed joints, indium increases the wettability of the filler metal on the diamond surface thus increasing the climb height and reducing the uneven wear rate, and the brazed joints have the best cutting performance when the filler metal is added with 1 wt% of indium element.