Novel Cold Spray Nanostructured Aluminum

Abstract

This paper discusses the introduction of a relatively new materials consolidation process, referred to as 'Cold Spray', which has been shown to meet the low-temperature, high velocity criteria for the production of dense, oxide-free metal-base nanostructured materials that may contribute to stronger near net-shape spray nanostructured components and as an enabling repair technology. When spraying nanostructured coatings, there are particular requirements in preserving the microstructure and functionality of the feedstock powder in the final bulk material. This is especially true when depositing temperature sensitive and readily oxidizing materials such as carbides, nitrides, and nanostructered metals. For these materials, the goal is to replace most, if not all, of the thermal energy (i.e., flame temperature) with kinetic energy (i.e., particle velocity) so as to retain the nanostructure without contributing to coating oxidation or porosity. Osmotic consolidation, pressure filtration, and tape casting have been used to produce consolidated nanostructured materials with limited thickness. The low temperature and high kinetic energy associated with the cold spray process allow for the retention of fine/nano grain structure, absence of phase change, capability for thick deposits, and promotion of compressive residual coating stress. These capabilities make the cold spray process an ideal approach to depositing nanostructured metal-base coatings, as well as nanostructured bulk materials. This paper will present data associated with the cold spray development and materials characterization of nanostructured 5083 aluminum.