Enhanced resistance to corrosion and hydrogen permeation due to tungsten partitioning induced phase and strain evolution in electrodeposited cobalt-tungsten coatings

The study focused on the electrochemical behaviour and hydrogen permeation of electrodeposited Co-W coatings with varying tungsten compositions. The coating with highest tungsten content (13 wt%) exhibited W-enriched nanoclusters, promoting galvanic coupling and reducing corrosion resistance. The tensile strain around these coherent clusters provided pathways for hydrogen to escape, increasing permeation rates. In contrast, the 6 wt% W coating exhibited superior corrosion resistance due to a favourable low-energy texture and forming stable oxides in corrosive environment. In this coating tungsten distributed in the solid solution and it has larger atomic size, created compressive fields hindering hydrogen pathways, enhancing resistance to permeation.