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

Diamond-based composites are widely used in cutting and wear-resistant applications. However, their brittleness limits their performance. Prior research has shown that metal binders can improve the mechanical properties of these composites. Despite this, the exact impact of multi-element alloys on sintering behavior and mechanical strength remains unclear. This gap motivated the investigation into how different binder compositions affect the microstructure and performance of diamond composites. The study of binder-diamond interactions under high pressure and high temperature is still limited. Understanding these interactions could lead to better composite design. Current methods for evaluating binder effectiveness rely on mechanical testing and microstructural analysis. No prior work had resolved the comparative performance of multi-element alloys versus single-element binders.

The aim of this study was to evaluate the performance of a Co₅₀Ni₄₀Fe₁₀ multi-element alloy as a binder in diamond composites. The researchers focused on comparing this alloy with pure cobalt as a binder material. They used high temperature and high pressure conditions to simulate industrial sintering processes. The study investigated how binder composition affects the sintering behavior and mechanical strength of the composites. The motivation was to identify a binder that enhances the toughness and strength of diamond composites. The researchers also aimed to understand the microstructural evolution during sintering. They tested two preparation methods: mixing-sintering and infiltration-sintering. The goal was to determine the optimal binder and process for industrial applications.

The study used two sintering methods: mixing-sintering and infiltration-sintering. Diamond-based composites were prepared with varying diamond content. The binder used was a Co₅₀Ni₄₀Fe₁₀ multi-element alloy. High temperature and high pressure (HTHP) conditions were applied during sintering. The phase diagrams of Co-C and Co₅₀Ni₄₀Fe₁₀-C were calculated at 6 GPa. Thermo-Calc software was used for the phase diagram analysis. The mechanical properties of the sintered composites were tested. Transverse rupture strength (TRS) was measured to assess performance.

The results showed that the Co₅₀Ni₄₀Fe₁₀ alloy improved the sintering of diamond compared to pure cobalt. The TRS of sintered diamond with the alloy binder was higher than with pure cobalt. Specifically, the TRS of the alloy-based composite reached 1360.3 MPa. This value was 19.2% higher than that of the cobalt-based composite. The alloy binder resulted in less metal residue in the polycrystalline diamond (PCD). The metal cluster area was smaller with the alloy binder. The metal distribution was more uniform in the alloy-based composites. These findings suggest that the alloy enhances the mechanical performance of diamond composites.

The authors concluded that the Co₅₀Ni₄₀Fe₁₀ alloy is more effective as a binder in diamond composites than pure cobalt. The alloy promotes better sintering and increases the transverse rupture strength. The reduced metal residue and more uniform distribution support this conclusion. The study shows that the alloy improves the mechanical properties of the composites. The results suggest that the alloy could be a better choice for industrial applications. The authors propose that the alloy’s composition contributes to these improvements. They note that the infiltration-sintering method may be more effective than mixing-sintering. The findings provide a basis for further optimization of binder materials.