Iron–tungsten alloys electrodeposited under direct current from citrate–ammonia plating baths

Fe–W alloys containing ~ 23–30 at.% tungsten were electrodeposited from citrate–ammonia solutions at different cathodic current densities. A characterization of the structural properties of these coatings is reported.The 8 to 15 μm thick Fe–W coatings obtained are smooth and nano-crystalline. The structure of such as-electrodeposited coatings evolves slightly with increasing cathodic current densities. Above 5 A dm− 2, micro-cracks appear in electrodeposited Fe–W coatings, and the oxygen content in the coatings increases. A nano-crystalline structure and a high tungsten content result in nanohardness of 13 GPa. The electrodeposited Fe–W alloys remain “nanocrystalline” after annealing up to 800 °C. After heating at 1000 °C, the nano-crystalline structure transforms into a microcrystalline one, and up to three phases are formed, namely FeWO4, Fe, and possibly Fe2W.