A Novel Preparation Approach of Mo₂(Fe_x, Ni_1–x)B₂ Solid Solution Powders

Mo₂FeB₂-based cermets exhibit promising industrial manufacturing applications due to their excellent mechanical properties, higher oxidation resistance, and thermal stability. In this study, ternary boride solid solution powders of Mo₂(Fe_x, Ni_1–x)B₂ were successfully prepared with a unique technique via employing B₄C powder as a boron source, Mo, Fe, and Ni powders as metal sources as well as Ca powder as the decarburization agent. The effect of the Fe/Ni ratio on the phase composition, morphological evolution and average grain size of powders was studied. The shift of diffraction peak in the XRD results and the homogeneous distributions of Mo, Fe, Ni, and B by the EDS energy spectrum validated the successful synthesis of ternary boride solid solution powders. The morphology of solid solution powders varied depending on the Fe/Ni ratio. For compositions with Fe/Ni ratios of 10 : 0, 7 : 3, and 5 : 5, the ternary solid solution powders exhibited pronounced spherical grains with average grain sizes of approximately 3, 1, and 1 μm, respectively. Conversely, when the Fe/Ni ratios were 3 : 7 and 0 : 10, the solid solution powders exhibited mixed morphologies of spherical (with diameters of approximately 1 μm) and prismatic grains (with lengths of about 8 μm and diameters of around 3 μm), corresponding respectively to the tetragonal and orthorhombic crystal structures of Mo₂NiB₂. Using ultrafine Mo powder as a raw material to boost reaction kinetics resulted in the product's stable phase being orthorhombic Mo₂NiB₂. Nonetheless, at a Fe/Ni ratio of 3 : 7, the product still consisted of orthorhombic and tetragonal Mo₂NiB₂ phases.