The Effect of Crystallization and Phase Transformation on the Mechanical and Electrochemical Corrosion Properties of Ni-P Coatings

This paper deals with the study of crystallization and phase transformation Ni-P coatings deposited on AZ91 magnesium alloy. Prepared samples were characterized in terms surface morphology elemental composition by means scanning electron microscopy energy-dispersive spectroscopy analysis. The results X-ray diffraction analysis differential calorimetry suggested that increasing phosphorus content caused to develop an amorphous character. Ni was observed at 150, 250, 300 °C for low-, medium- high-phosphorus coatings, respectively. crystallite size increased temperature decreasing P content. Conversely, presence Ni3P a maximum peak 320 coating, whereas shifted higher temperatures An increase microhardness due arrangement atoms precipitation observed. deposition as-deposited led improvement corrosion resistance AZ91. However, heat treatment resulted deterioration properties formation microcracks.