Microstructure and texture of Al coating during kinetic spraying and heat treatment

Abstract

Microstructure and texture formation of an Al coating during kinetic spraying (or cold gas dynamic spraying) and heat treatment were investigated. Coating formation by kinetic spraying is based on super-sonic collision of in-flight micron-sized particles and their severe interfacial plastic deformation under ultra-high strain rates (1.0 x 10(6)-0.5 x 10(9) s(-1)), which induces adiabatic shear instability. Shear texture, 45 degrees-rotated Cube {001} < 110 >, and static recovered microstructure were formed at the interface of Al during kinetic spraying because Al has the equivalent slip system {111} < 110 > of a face-centered cubic having high stacking fault energy (SFE). During heat treatment, discontinuous recrystallization and grain growth led to transformation of the shear texture into a strong Cube texture, {001} < 100 >, and misorientation angle transition. Given the mechanical and physical properties of the Al, metallurgical mechanisms of microstructure and texture formation of kinetic-sprayed and heat-treated Al coatings were suggested based on transmission electron microscopy and electron backscatter diffraction analysis.