Effect of boron content and crystalline structure on hardness in electrodeposited Ni-B alloy films

► Hardness of electrodeposited Ni-B films depended on their crystalline structure. ► Regardless of boron sources, Ni-B films with X-ray amorphous structure showed high hardness. ► Effect of boron content on crystalline structure (i.e., hardness) depended on the type of boron sources. ► Heat-treatment drastically affected crystalline structure and hardness of Ni-B films.