Amorphization of Ni-Si-C ternary alloy powder by mechanical alloying

In an attempt to prepare amorphous or nanocrystalline Ni powder by mechanical milling, a selected amount of hard particles of SiC were added to enhance the milling effect. It was found that amorphization took place when the mixture of Ni-28 at% SiC was tested. Heating of the amorphous powder led to the formation of crystalline phases Ni and Ni31Si12. Single phase Ni31Si12 was formed when heating to 600 degrees C. When Ni, Si, and C powders mixed at the same composition were milled, amorphization did not occur. Instead, the crystalline phase Ni31Si12 formed directly. It was believed that the strong and hard particles of SiC helped to fracture the Ni powder to form smaller crystallites and SiC was then embedded within Ni. A high concentration of defects in the Ni powder was established. Amorphization of Ni then took place to reduce the surface and defect energies.