Optimization of Microstructure and Properties of Brazed Diamond Interface Controlled by Micro-Mn Alloying of Cu Based Filler Metal

Abstract

In this experiment, the brazing of diamond with Cu-Sn-Ti-Ga filler metal was investigated in depth, aiming at reducing the thickness of TiC layer, regulating the microstructural distribution at the interface between diamond abrasive grains and filler metal, and exploring the optimum amount of Mn element to be added. The microscopic interface between the cast filler metal and the post-brazing specimen was analyzed in detail using scanning electron microscope and energy spectrometer, and the effect of Mn element on the interfacial structure was investigated in conjunction with the first nature principle. The results show that with the increase of Mn element in the Cu-Sn-Ti-Ga filler metal, the supercooling degree of the filler metal increases, the Sn3Ti5 phase becomes fine, and the content of eutectic organization increases. 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 decreases. The smoothest filler metal and the smallest porosity at the diamond-grain-substrate interface can be observed when the addition of Mn reaches 4 wt.%. The results of the first-principles calculations further validate that manganese reduces the titanium-catalyzed diamond graphitizing, which in turn reduces the thickness of the TiC layer as well as the deviation of titanium at the interface. In addition, friction and wear tests show that the samples prepared at a Mn addition of 4 wt.% has the best cutting efficiency and the highest service life.

Keywords: Cu-Sn-Ti filler metal, Microstructure, Machining performance, First Principle