Interface characteristics and fracture behavior of brazed polycrystalline CBN grains using Cu–Sn–Ti alloy

Polycrystalline CBN grains were brazed onto AISI 1045 steel matrix using Cu–Sn–Ti brazing alloy. Brazing temperature was 880 °C, 900 °C, 920 °C respectively, and the holding time was 8 min. Interface characteristics, elemental distribution and fracture behavior were analyzed in detail by means of scanning electron microscopy, energy dispersive spectroscopy and testing machine for grain compressive strength. The maximum value of the mean compressive strength of brazed PCBN grains reached 879.3 MPa when the brazing temperature was 900 °C. The resultants layer composed of TiN, TiB2, TiB and TiAl3 was formed at grain/alloy interface. Elemental distribution showed that Ti mainly concentrated within the interface zone. The intercrystalline fracture along the CBN/CBN particle boundary was the main fracture modes of brazed polycrystalline CBN grains.