Sliding wear resistance of Mo_SS-toughened Mo₂Ni₃ Si metal silicide alloys at elevated-temperature

Commercially pure molybdenum, nickel and silicon elemental powders were selected as raw materials. Mo₂Ni₃Si alloy consisting of molybdenum-based solid solution (Mo_SS) primary dendrites and ternary metal silicide Mo₂Ni₃Si matrix was fabricated using laser melting deposition manufacturing process. Wear resistance of the alloy was evaluated on a pin-on-disc tester in the range of 400-550°C. The morphologies of worn surface and subsurface was characterized by SEM. Results showed that the Mo_SS-toughened Mo₂Ni₃Si alloy exhibits abnormal dependence of wear on temperature, which is that wear rate decreased as temperature increased. The worn surface of the alloy was very smooth and clear without any characteristics of micro-cutting and plowing. Slight oxidation of Mo_SS dendrites was observed on the worn surfaces in the test temperatures. Mo₂Ni₃Si ternary metal silicide played dominant role in resisting the wear. Propagation of micro-cracks and micro-spalling in the Mo₂Ni₃Si matrix were restrained by the ductile Mo_SS dendrites. The main failure mechanisms of the Mo_SS-toughened Mo₂Ni₃Si alloy under elevated-temperature sliding wear were soft abrasion and slight oxidation of Mo_SS phase.