Microstructural Evolution of Diamond-Based Composites at High Temperature and High Pressure.

Improving the toughness of diamond composites has become an industrial demand. In this work, Co 50 Ni 40 Fe 10 multi-element alloy was designed as binder for diamond-based composites prepared by high temperature and high pressure (HTHP). Two methods of mixing-sintering and infiltration-sintering were used to prepare diamond-based composites with different diamond contents. The phase diagrams of Co-C and Co 50 Ni 40 Fe 10 -C at 6 GPa were calculated by Thermo-Calc. The results show that Co 50 Ni 40 Fe 10 multi-element alloy promotes the sintering of diamond powder than element Co. The transverse rupture strength (TRS) of sintered diamond with Co 50 Ni 40 Fe 10 (Co 50 Ni 40 Fe 10 -75 vol% diamond) is higher than that of Co-Comp (Co-75 vol% diamond). The TRS of polycrystalline diamond (PCD) with Co 50 Ni 40 Fe 10 alloy binder is up to 1360.3 MPa, which is 19.2% higher than Co-PCD. Compared with Co, using Co 50 Ni 40 Fe 10 as binder results in a less metal residue in PCD, while the metal cluster area is smaller and the metal distribution is more uniform.