Microstructure and Mechanical Properties of Arc-Melted NiSi11Cx Alloys

Functional materials such as nickel silicides (Ni3Si) are considered promising materials for building complex and strong structures. They have proven to have a high melting point, low electronic resistivity, excellent corrosion resistance, and thermally stability, however, their overall performances are still challenging due to their brittleness. Therefore, it is essential to prepare high-strength nickel silicide-based materials to improve their toughness. In the present study, arc melting has been utilized to synthesize nickel silicide (NiSi11, wt%) and carbon (C) alloyed nickel silicide (NiSi11Cx, x = 0.2, 1 wt%) with varying amounts of C aiming to improve the microstructure and mechanical properties of the alloy. The NiSi11 and NiSi11Cx alloys were characterized by Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), and microhardness tests. Results show that the NiSi11 alloy comprises lamellar-like eutectic Ni3Si and Ni solid solution phases. After alloying with C, the microstructure of the Ni-rich solid solution and Ni3Si phase is changed to a relatively fine-scale morphology, and C is mainly dissolved in the Ni-rich solid solution phase. The microhardness of the alloys is increased with the addition of C, which is mainly attributed to the microstructure refinement and solid solution strengthening obtained through C addition.