Cold Spray Additive Manufacturing of NiTi Alloys

Cold spray additive manufacturing (CSAM) is a solid state additive manufacturing technique in which powder particles are accelerated to supersonic velocities and impacted onto a substrate, causing plastic deformation resulting in adhesion and buildup of the particles. CSAM can be used to fabricate parts, but also for surface treatment, repair, and joining applications. Cold spray processing of NiTi alloys (both pseudoplastic and pseudoelastic) is particularly challenging, due to the vastly different deformation behavior from traditional alloys used in this process (Al, Fe, Ni, etc.). This effort shares the approach and results of cold spray processing numerous powder/substrate combinations within the following three categories: 1) NiTi (NiTi5, NiTi9) powder onto structural substrates (e.g. Al 6061 and 316 SS); 2) structural powder (Al 6061, Ti-6Al-V4, 316 SS, CP Ni, CP Ti) onto NiTi substrates (NiTi 5, NiTi 9); and 3) NiTi (NiTi5, NiTi9) onto NiTi (NiTi5, NiTi9). Materials and mechanical characterization of both the feedstock powder and the prints was performed, and used to improve process parameters of subsequent prints.