Interfacial microstructure of pre-brazed diamond composite segments using Ni-Cr composite alloy

Pre-brazed diamonds were fabricated by using diamonds and Ni-Cr composite brazing alloy, which were consisted of Ni-Cr alloy and A alloy. Brazing temperature was 1 050 ℃ and the holding time was 30 min. Abrasive composite segments consisting of the pre-brazed diamonds and metal matrix were sintered at the heating temperature of 810 ℃ for the dwell time of 4 min. The static compressive strength of the pre-brazed diamonds and the bending strength of the abrasive composite segments were measured. The interfacial microstructure of the pre-brazed diamonds and the composite segments fracture surface were characterized. Results obtained show that the chemical combination interface between diamonds and Ni-Cr composite alloy was developed when pre-brazing and the thermal damage to the diamonds was greatly reduced. The bending strength of the abrasive composite segments (10%-50%) was much higher than that of the conventional segments. In the composite segments the metallurgical bonding between the pre-brazed diamonds and metal matrix was formed and the diamonds were embedded firmly.