Sintering behaviors of fine-grained cBN–10 wt.% Al3.21Si0.47 system under high pressure

Sintering behaviors of fine-grained cBN–10 wt.% Al3.21Si0.47 system under high pressure of 5.0 GPa and temperatures up to 1600 °C were investigated. By analyzing the phase components of sintered samples through x-ray diffraction (XRD), and detecting the in-situ electrical resistance signal during high pressure and high temperature (HPHT) sintering, we suggested the reactions between cBN and Al3.21Si0.47 happened at about 600 °C. Between 600 °C and 900 °C, AlN, AlB2 and Si formed, while above 1000 °C, the content of AlN, AlB12 and Si phases increased with AlB2 disappearing. Scanning electron microscope (SEM), Vickers hardness tests as well as cutting performance tests showed that the well-sintered samples in cBN–10 wt.% Al3.21Si0.47 with homogeneous microstructure and best mechanical performance could be obtained at the sintering P–T condition of 5.0 GPa, 1400 °C for 10–15 min.

► Sintering behavior of fine-grained cBN–10 wt.% Al3.21Si0.47 was investigated.
► The reactions between cBN and Al3.21Si0.47 happened at about 600 °C.
► The highest hardness of around 36 GPa for the samples was achieved.
► The well sintered samples could be obtained at 5.0 GPa, 1400 °C for 10–15 min.