Impact of ultrasonic vibration on microstructure and mechanical properties of diamond in laser brazing with Ni–Cr filler alloy

Abstract An attempt to increase the strengths of bonding between diamond and filler metal in producing high-precision machining tools was made in this paper by proposing new ultrasonic-assisted laser brazing (UALB) technique in which the UALB process was performed using a fiber laser and Ni–Cr filler alloy, followed by the paraxial feeding of diamond powder. In addition, to examine the impact of an ultrasonic vibration on the mechanical properties of diamond at its bonding interface, the brazing process was carried out with and without suppression in ultrasonic vibration, and the microstructure and mechanical properties of diamond at the bonding interface were observed, measured and compared. The results showed that the ultrasonic assistance had improved the strengths of the bonding of diamond with the filler alloy by reducing surface cracks, increasing the wettability of molten filler, and forming and crystalizing directional carbides of Cr3C2 and Cr7C3 with a higher density.