The structure and microhardness of Ni-B electrodeposited coatings subjected to low temperature annealing
The structure and microhardness of electrodeposited Ni-B coatings subjected to low temperature annealing at 520 K have been investigated. It is shown that the low-temperature annealing of crystalline Ni-B coatings is accompanied by an increase in microhardness and the lattice parameter of the solid solution of boron in nickel. It is concluded that the increase of microhardness and lattice parameter of Ni-B solid solution during annealing is due to the transition of the boron atoms from the substitution positions to the interstitial positions occurring by dissociative Frank-Turnbull mechanism which is accompanied by the formation of covalent bonds between boron and nickel atoms.