Effect of vacuum heat treatment on tensile strength and fracture performance of cold-sprayed Cu-4Cr-2Nb coatings

The previous study [1] indicated that dense thick Cu-4Cr-2Nb coatings could be formed by cold spraying, and the post-spray heat treatment could significantly influence the microstructure and microhardness of the as-sprayed Cu-4Cr-2Nb coatings. In this study, the tensile strength and fracture performance of the Cu-4Cr-2Nb coatings after annealing were investigated. The vacuum heat treatment was conducted under 10 ^-2 Pa at 850 °C for 4 h. Results showed that the heat treatment had a great contribution to the healing-up of the incompleteness of the interfaces between the deposited particles. In addition, the coating microhardness decreased from 156.8 ± 4.6 Hv _0.2 for the as-sprayed coatings to 101.7 ± 4.5 Hv _0.2 for the annealed ones. The mean tensile strength of the annealed coatings was approximately 294.1 ± 36.1 MPa compared to that of 45.0 ± 10.5 MPa for the as-sprayed ones, which results from the partially metallurgically bonded zones between the deposited particles inducing by the heat treatment process.