A Study of the Mixed Powders Interaction Behaviour Upon Impact in Cold Spray

Cold spray of mixed metal powders has been reported to improve the deposition efficiency (DE) of the component powders. However, the mechanisms behind such improvements are often not well understood. In this work, 316L/Fe mixed powders were studied as part of an overall effort to fabricate controlled biodegradable composites. Two different sizes (~45 μm, ~25 μm) of 316L and Fe powders, as well as four 316L/Fe binary mixtures, were cold spray deposited and the DE was measured. The variations of the mixed powder DE as a function of the feedstock Fe wt.% and the cold spray process parameters are discussed and the mixed powder interaction behaviour upon impact is proposed. It is concluded that the combined effects of tamping and retention are the main mechanisms that lead to the improved DE of mixed 316L/Fe powders.