Phase composition, microstructure, and mechanical properties of PcBN composites with Ti and Ti-Al binders: Effects of holding time and synthesis pressure

This paper prepared cBN-Ti and cBN-Ti-Al system composites by high-temperature and high-pressure method using cubic boron nitride powder, titanium powder, and aluminum powder as raw materials. The phase composition, microstructure, and mechanical properties of the two systems based on varying holding time and synthesis pressure were studied and analyzed. The results showed that when the holding time was <480 s, the mechanical properties of the composites worsened for the intermediate products remained. The composites of the cBN-Ti and cBN-Ti-Al systems exhibited their highest bending strengths of 779 MPa and 957 MPa, respectively, after being held for 480 s. Both composites' hardness and bending strength increased as the synthesis pressure increased. At a synthesis pressure of 6 GPa, the hardness and bending strength of the cBN-Ti system composite were 33.3 GPa and 804 MPa, respectively. Similarly, the cBN-Ti-Al system composite showed a hardness of 33.3 GPa and a bending strength of 994 MPa at the same pressure.