The heat treatment effect on the structure and mechanical properties of electrodeposited nano grain size Ni–W alloy coatings

The Ni–W alloy coatings with tungsten content from 32.5 to 61.2 wt.% were prepared in this study by electro-deposition. Experimental results show that the grain size of Ni–W coatings evaluated by XRD decreased with increasing tungsten content in coatings, however, the micro-hardness increased with increasing tungsten content. As-deposited Ni–61.2 wt.%W coating has amorphous-like structure and the grain size is around 1.5 nm, after annealing at 500 °C, the hardness of the coating is promoted to 1293 Hv owing to formation of Ni4W and NW precipitates. In addition, the heat-treated Ni–W coatings show a better wear resistance than the as-plated Ni–W coatings.