Phase field modelling of microstructure evolution of cold-sprayed Ni-Ti composite upon post-spray heat treatment

The interesting physics involved in the cold spray (CS) including high-strain-rate, adiabatic and severe plastic deformation results in a complex structure at different length-scales that directly determines the properties of the deposits. Therefore process-structure-properties (PSP) linkages explorations are pivotal. Integrated computational materials engineering (ICME) along with experimental analyses are required to evaluate materials properties/behaviour. FEM modelling is used to simulate the materials’ thermomechanical response and field variables evolution, i.e stress, strain, strain rate, and temperature, at structural scales. Molecular dynamics modellings of nano-particle impact provided useful insights into atomic-scale phenomena while the modelling of microstructure evolution in micro-scale has yet to be investigated. We developed and implemented a thermodynamic phase field simulation method to capture the structure evolution of CS composite Ni-Ti deposit upon post-spray heat treatment (PSHT) in microstructure scale. The external or internal stimuli i.e. heat and strain either generated in the system because of phase transformation or stored as internal energy upon CS process are accounted for. The interface mobility and microstructure development are calculated by minimization of Gibbs free energy of the system. Comparison of the simulated microstructure with experimental results confirms that this model precisely predicts the microstructure evolution of the CS deposits upon PSHT.