Microstructural evolution and mechanical properties enhancement of a cold-sprayed CuZn alloy coating with friction stir processing

An innovative hybrid process combining two very effective solid-state techniques which are Cold Spray (CS) and Friction Stir Processing (FSP), was proposed to fabricate a high-strength ultrafine-grained CuZn coating. Results show that the cold-sprayed coating obtained exhibits an elongated microstructure with 78.42% of low-angle grain boundaries. Following FSP, there appear ultrafine grains with 90.47% of high-angle grain boundaries and a blend of α, β″ and γ phases, while the as-sprayed coating is mainly α-phased. Significant mechanical properties enhancement is achieved, i.e. with the ultimate tensile strength increasing from 87.2 MPa to 257.5 MPa and the fracture elongation increasing from 0.17% to 0.81%. The precipitates have a significant effect on the fracture behavior of friction-stirred coating.