Impact-induced deformation and microstructural evolution in cold-spray deposition of aluminum alloy–quasicrystal composite: A characterization perspective

This study systematically investigates the deposition behavior and microstructural changes in AA6061 (AA) coatings reinforced by Al-based (AlCuCrFe) quasicrystalline (QC) particles fabricated via high pressure cold spray (CS). While depositing a CS coating exclusively from naturally brittle and hard QC particles is challenging, blending them with softer AA particles facilitates dynamic interactions. The ductile deformation of AA particles facilitates the entrapment of hard, fracture-prone QC particles and their fragments, while the AA matrix undergoes heterogeneous deformation due to severe plastic deformation by high-velocity impacts. The repeated and multidirectional hammering by QC particles caused a micro-forging and intensive plastic flow of AA, resulting in vortex-like deformation of matrix and improved interfacial bonding between the matrix and reinforcement. This results in complex microstructural evolution in AA, including substantial grain refinement (exceeding 50 %) and formation of bimodal nanocrystalline and ultrafine grain structures, through favoring dynamic recrystallization. Consequently, structural densification and about + 25 % increase in nanohardness of the Al phase within the composite contribute to the overall strengthening of the AA-QC structure. Through a detailed investigation of impact-induced microstructural evolution, this work deepens the understanding of AA-QC composite deposition, offering a solution for extended material performance in demanding environments.