Cold gas dynamic spraying of a high temperature Al alloy

The present paper describes a study of the influence of cold spraying on the microstructure, heat treatment response and mechanical behavior of a high temperature 2618 aluminum alloy (Al–Cu–Mg–Fe–Ni) modified with 0.16 wt.% Sc. The microstructure of the starting powder consisted of a network of Al2CuMg phase on the grain boundaries of the Al matrix, along with Al9FeNi precipitates for atomized powder particles larger than 20 μm, and a cellular solidification structure for particles smaller than 20 μm. The coating after deposition was composed of the same microstructure features as observed in the feedstock powder but highly deformed. The observed overall deformation suggests the occurrence of localized adiabatic shear instability at the particle/particle boundary and adiabatic deformation softening at the powder interior during splat formation. The coating hardness was similar to the one obtained at the peak aged condition (T6). The coating aging response was influenced by the presence of Al7FeCu2 particles that depleted the matrix from Cu, reducing the overall hardness and overcoming the benefits of Sc addition.