COMPUTATIONAL MODELING OF EXTREME PARTICLES DEFORMATION AND GRAIN REFINEMENT DURING COLD SPRAY DEPOSITION

When deposition parameters are carefully set, cold spraying can successfully deposit composite coatings with customized characteristics. To avoid conducting repeated experimental trials, numerical simulations are critically needed to optimize the cold spray deposition parameters. During cold spraying of the composite layer, extreme particle deformation and temperature rise occur due to the complex interactions among dissimilar particles; hence, the coating layer properties vary across the thickness. In the cold spray literature, particle grain refinement is not considered in numerical simulation studies. The present study uses a physics-based hybrid computational technique to simulate multi-material particle deformation during the cold spray deposition of Ni-Al2O3 coating utilized for wear applications. The hybrid approach effectively combines point cloud and finite element models to simulate particle deformation and interactions during the cold spray process. An attempt to predict the grain refinement due to extreme deformation and dynamic recrystallization of deformed particles is made for the first time using the phase field method (PFM). The strain field and temperature distribution are used to predict the grain size evolution in the deformed particles. The numerical simulation results are validated by comparing them with those of experiments. The results show that the softer Ni (matrix) particles undergo higher deformation, and their deformation pattern is strongly affected by the presence of neighboring Al2O3 particles. Due to higher plastic strain and strain rate, the particle’s deformation affects the grain size evolution, mainly in the Ni matrix material. The extremely deformed regions, such as Ni particle interfaces and edges, demonstrate the possibility for grain refinement according to simulation data on strain rate, temperature, and deformation among dissimilar particles. The current study aims to establish a reliable numerical methodology for the optimization and prediction of properties of composite made from cold spraying.