Microstructure and properties of polycrystalline diamond with AlCoCrFeNi2.1 eutectic high-entropy alloys as binder

The performance of polycrystalline diamond (PCD) tools largely depends on the adhesion and catalyzing effect of the binder phase. In this study, AlCoCrFeNi_2.1 eutectic high-entropy alloy (HEA) was used as a new binder material to synthesize the PCD samples. First-principles calculations showed that the interface strength between HEA and diamond is better than that between cobalt and diamond, suggesting that the HEA/PCD combination has the potential to exhibit better properties than the conventional cobalt/PCD tools. PCD samples with HEA as the binder phase were successfully synthesized using high-pressure and high-temperature conditions of 8.0 GPa and 1500–1700℃. Several key performance indicators, including thermal expansion coefficient, Vickers hardness, transverse rupture strength, compressive strength, and wear resistance were measured to comprehensively evaluate the overall performance of the well-sintered HEA/PCD. The results showed that, compared with conventional cobalt/PCD, the HEA/PCD exhibited a lower thermal expansion coefficient and reduced graphitization of diamond at high temperatures above 920 K. HEA/PCD also demonstrated better mechanical properties than Co/PCD, including higher hardness, and greater transverse rupture strength and compressive strength. Moreover, over the same cutting distance against the granite block, HEA/PCD tools exhibited significantly lower wear loss than Co/PCD, indicating superior wear resistance. This study provides new insights and strategies for the design and optimization of PCD binders and PCD tools.