Interfacial bonding mechanism of high-pressure sintered Al-Ti-cBN composites

摘要

The cBN powder with Al,Ti additives was sintered on a hinge cubic press with a sintering pressure of 5.6 GPa, a sintering temperature of 1550 degrees C, and a sintering time of 180 s. SEM, EDS, XRD and TEM were used to analyze the micro-morphology, element distribution and phase composition of the samples, and the microstructure and interface bonding mechanism of the sample were discussed. The results showed that the exothermic reaction of cBN with Al and Ti resulted in the reaction product AIN transforming into a liquid phase under high temperature conditions, which dissolved the reversely transformed hBN and resulted in the precipitation and growth of cBN grains, forming cBN cBN bonding, and it was found that cBN and cemented carbide interface existed 12-13 mu m special melt alloy transition zone, the main components of the interface were Co and AITi alloys. This special interfacial structure is formed by the high-pressure infiltration of the AITi alloy melts firstly and then the Co melts, which can form a continuous three-dimensional network of Co and AITi alloys thus forming strong bonding in the interface of cemented carbide and cBN layer.