Abstract
Nickel titanium is promising cavitation erosion resistant material. Using NiTi in bulk for components might not be feasible due to its poor workability, as well as the high material and processing costs. Surfacing components with its coating is effective for utilizing the good erosion properties of NiTi intermetallic compounds. In this study, a method to prepare NiTi intermetallic compound coatings in-situ through annealing of the cold-sprayed Ni(Ti) metastable coating was investigated. A nanostructured Ni(Ti) solid solution alloy powder was prepared by ball-milling process. The cold sprayed Ni(Ti) alloy coating was used as the precursor coating. The effect of annealing temperature on the microstructure in-situ evolution of Ni-Ti intermetallic compound in cold-sprayed coating was investigated. The morphology and phase composition of the powders milled for different durations and the microstructure of the as-sprayed coating were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that after annealing at 950°C the Ni(Ti) alloy was transformed to intermetallic phases. NiTi, Ni3Ti and NiTi2 intermetallic phases coexisted in the annealed coating.