Microstructure and tribological properties of NiMo/Mo2Ni3Si intermetallic “in-situ” composites

Wear resistant NiMo/Mo2Ni3Si intermetallic “in-situ” composites with a microstructure of ternary metal silicide Mo2Ni3Si primary dendritic, the long strip-like NiMo intermetallic phase, and a small amount of Ni/NiMo eutectics structure were designed and fabricated using molybdenum, nickel and silicon elemental powders. Friction and wear properties of NiMo/Mo2Ni3Si composites were evaluated under different contact load at room-temperature dry-sliding wear test conditions. Microstructure, worn surface morphologies and subsurface microstructure were characterized by OM, XRD, SEM and EDS. Results indicate that NiMo/Mo2Ni3Si composites have low fiction coefficient, excellent wear resistance and sluggish wear-load dependence. The dominant wear mechanisms of NiMo/Mo2Ni3Si composites are soft abrasion and slightly superficial oxidative wear.

Research highlights
► Wear resistant NiMo/Mo2Ni3Si intermetallic “in-situ” composites was fabricated successfully with Mo–Ni–Si powder blends as the starting materials. Microstructure of the NiMo/Mo2Ni3Si composites consists of Mo2Ni3Si primary dendrites, binary intermetallic phase NiMo and small amount of Ni/NiMo eutectics structure. The NiMo/Mo2Ni3Si composites exhibited high hardness and outstanding tribological properties under room-temperature dry-sliding wear test conditions which were attributed to the covalent-dominant strong atomic bonds and excellent combination of strength and ductility and toughness.