The role of pre -alloyed powder combined with pressure -less microwave sintering on performance of superhard materials

In this work, we fabricated metal-diamond composite material with excellent mechanical properties via pressure-less microwave sintering by using pre-alloyed metallic powder as the raw materials. The elementary substance metallic powder formula was simultaneously sintered as a comparative test. A scanning electron microscope (SEM) was used to analyze the microstructural morphology information of samples. Phase transitions were studied by an X-ray diffraction (XRD) technique. The hardness, bending strength and relative density of samples were tested to evaluate their mechanical properties. Raman spectroscopy was used to investigate the diamond graphitization. The results show that the formula of pre-alloyed metallic powder exhibited better heating efficiency under the microwave irradiation; in turn, the samples can reach targeted sintering temperature ahead of the elementary substance metallic powder samples. Furthermore, the samples sintered via pre-alloyed powders display excellent mechanical properties; the relative density, hardness and bending strength can reach 98.8%, 101.5 HRB and 1065.9 MPa, respectively. This promotional behavior can be attributed to the pre-alloyed characteristic of raw powders that facilitates the uniform distribution of metal elements and a more thorough alloying reaction even if the sintering temperature is below 900 °C. It is demonstrated that the pressure-less microwave sintering will be feasible in the fabrication of metallic matrix diamond super-hard tool bits by utilizing the pre-alloyed powders as the raw material. The combination of microwave sintering and pre-alloyed powder is expected to provide a new strategy with efficient and low cost for the preparation of super-hard material products.