We investigated the structure change, surface properties (roughness, porosity, and hardness), tribological, and electrochemical performances of HVOF sprayed Ni20Cr-10W-9Mo-4Cu-1C-1B-1Fe (Diamalloy-4006) coatings before and after laser irradiation. The results showed that the friction and wear resistance of the coatings were improved significantly with an optimized laser irradiation process. The improvement can be attributed to the improved roughness and hardness, as well as the formation of oxides Cu x O and Cr 2 O 3 tribofilms. With the laser irradiation treatment, the local corrosion of the coating had a decrease and the selective corrosion resistance of the Diamalloy-4006 coating was improved as a result of the decreasing the size and number of the pores, especially compact interface achieved by laser irradiation.

The current research investigated the annealing behaviour of the electrodeposited Ni-Zr and Ni-Al composites from 475 to 675 K using an X-ray diffractometer line profile analysis (LPA) technique. The results showed that the grain size increased and microstrain decreased with an increase in the annealing temperatures and annealing times. The grain growth activation energies Q of 53.2 kJ mol −1 for Ni-Zr composite and 79.4 kJ mol −1 for Ni-Al composite were obtained based on the LPA technique. This smaller grain growth activation energy of the composite compared with the pure nickel could be ascribed to the higher microstrain and nanocrystalline crystallites. The residual tensile stress of the as-deposited composite changed to compressive stress state after annealing treatment and increased with annealing temperatures.

Ni–Al–Ti nanocomposite coatings were synthesized by electrodeposition. The tailoring role of Al and Ti particles in the co-deposition behaviors of nanocomposite coatings was comprehensively investigated by analyzing the time-dependent current density and electric field near the co-deposited particles. The results showed that the Al and Ti particles caused different co-deposition behaviors of Ni deposits, consequently bringing in the gradual increase in the surface dendritic structure, the refinement of grain sizes, and the decrease in the [200] fiber texture of the nanocomposite coatings with the decrease in the Al/Ti weight ratio. COMSOL simulations verified the different co-deposition mechanisms of Ni grains near the two kinds of particles, which was vitally determined by the different conditions of current density and electric field near the particles. The micro-hardness results revealed that the decreased Al/Ti weight ratio led to enhanced micro-hardness of the nanocomposite coating; in addition, the maximum hardness of the nanocomposite coating was 604.3 HV0.2 for an Al/Ti weight ratio of 1:4. Thus, the time-dependent current density and electric field near co-deposited Al and Ti particles determined the microstructure and property of the Ni–Al–Ti nanocomposite coatings.