| Résumé | Cold spray of mixed metal powders is of significant research interest as it often generates unpredictable effects on deposition efficiency (DE) and porosity. Thus, analyzing the cold spray characteristics of two metal powders can lead to a better understanding of mechanisms of cold spray deposition and consolidation. In this study, average 43 μm 316L stainless steel and 22 μm commercial purity Fe powders were used as feedstock. The following coatings were deposited through cold spray: single component 316L and Fe, and their binary composites with different feedstock mixing compositions of 316L-20 wt% Fe (20Fe), 316L-50 wt% Fe (50Fe), and 316L-80 wt% Fe (80Fe). Results show that the composite coating microstructure and cold sprayability (DE, porosity, coating bond strength) exhibit strong effects of mixing powders. Several particle and coating metrics (particle in-flight velocity, coating flattening ratio, coating microhardness) were also measured to further exhibit the effects of mixing. To explain these observations, a multiple particle arrangement model based on the calculated particle number fraction of the mixture is proposed. Using this model, mechanisms associated with the deposition of bimodal size 316L/Fe powder mixtures are discussed, and the effects of mixing powders on the cold spray characteristics are explained accordingly. |
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