Microstructural Heterogeneity

The low working temperature of cold spray deposition offers the unique possibility of mixing different volume fractions of micro and nanocrystalline powder particles to obtain bimodal structures with heterogeneous arrangement of crystalline phases. While the improved mechanical properties of the bimodal structures rely on the full metallurgical bonding within the bulk material, partially bonded inter-particle interfaces, crystal defects (dislocations, grain boundaries, etc.) induced upon high-velocity impacts, and the consequent brittleness of the cold spray deposits, would distinguish this technology from the current methods employed for fabrication of bulk heterogeneous structures. We explore different strategies to address these challenges and exploit the potential of cold spray in modulating the mechanical properties of the deposits by inducing microstructural heterogeneity controlling the volume fraction of the powder constituents with mismatching structures.