Nickel aluminide superalloys created by SHS of nano-particle reactants

Advancements in nanotechnology for material processing have spurred the development of superalloys that provide improved protection against corrosion and wear. Nano-scale reactant particles offer unique thermal properties and increased homogeneity that may improve the micro-structural features and macroscopic properties of the final product. In this study up to 10-wt % nano-scale molybdenum tri-oxide (MoO₃) particles were added to micron scale nickel (Ni) and aluminum (Al). The goal was to produce a superalloy by generating excessively high heating rates and adding an oxidizer that would produce small quantities of Al₂O₃ (a strengthening agent) within the microstructure of the alloy. Experiments were performed on pellets pressed to 60% theoretical maximum density. Ignition and flame propagation were examined using a CO₂ laser and imaging diagnostics that include a copper-vapor laser coupled with a high-speed camera. Product microstructure was examined using scanning electron microscopy. Abrasion testing was performed to evaluate the wear resistance properties of the superalloy. Results show that adding MoO₃ increases the flame temperature and produces greater ignition sensitivity. Also, small quantities of MoO₃ produce a more homogeneous microstructure and increase the overall wear resistance of the product.