Investigation of struce and properties of ni-cowb composites produced bu sintering

In this study, Ni–CoWB composites were produced from Ni–Co–W–B metallic-glass alloys with different boron contents by sintering, and the microstructural, mechanical, and chemical properties of these composites were systematically investigated. Amorphous ribbons fabricated by melt spinning were ground into powders, and these amorphous powders were densified at various temperatures by spark plasma sintering (SPS). Sintering of the amorphous powders yielded low-porosity composites through the co-precipitation of a Ni solid solution and the CoWB phase. Density measurements indicated high sinterability and low porosity in both composites. Microstructural analyses revealed CoWB volume fractions of 19% and 37% for the Ni51Co18 W18B13 and Ni37Co22W22B19 compositions, respectively. Vickers hardness values were measured as 630 HV and 754 HV, and the fracture toughness for both composites was at least 25 MPa·√m. Wear tests showed wear rates on the order of 6 × 10-7 mm³/N·m for both materials. Corrosion experiments demonstrated that the sintered composites exhibited lower resistance than heat-treated samples, which was attributed to residual porosity. High-temperature oxidation experiments at 800 °C and 900 °C indicated oxidation resistance superior to that of most cermets, with the Ni37Co22W22B19 composite in particular exhibiting higher resistance. In conclusion, the Ni–CoWB composites produced here combine high wear resistance, robust fracture toughness, and strong oxidation resistance, highlighting their potential for applications where wear resistance at elevated temperatures (≥ 700 °C) is critically important.