Microstructure Characterization of In-Situ Al₅Fe₂ Intermetallics Particles Reinforced Al Matrix Composite Coating by Annealing Treatment of Cold Sprayed Precursor

This study investigates the effects of feedstock composition and annealing temperature on cold-sprayed aluminum-iron deposits. Commercially available Al and Fe powders mixed in ratios of 55:45, 75:25, and 85:15 were cold sprayed on aluminum substrates, producing dense coatings that were subsequently annealed at 500 and 550 °C. Solid diffusion reactions between Fe and Al produced Al₅Fe₂ intermetallic compounds, the morphology and content of which were found to depend on annealing temperature and the composition of the as-sprayed deposit. The Fe particles in the Al matrix were fully consumed via compounding reaction with Al at 550 °C. At higher temperatures, however, the intermetallic particles begin to crack possibly due to large tensile stresses.