Abstract
The dependence of physicochemical properties, including microhardness, magnetism, morphology, crystalline information, roughness factor and hydrogen evolution ability, on the phosphorus content, varying from 0 to 28 atomic percentage (at.%), of Ni-P deposits with annealing in air at eight temperatures (i.e., 100, 200, 300, 400, 500, 600, 700 and 800°C) were systematically compared. The microhardness reached a maximum at 400°C due to the crystallization of Ni and Ni <sub>3</sub> P at 400°C and the significant diffusion of Cu into the Ni-P deposit at temperatures ≥500°C, confirmed by the depth profiles of Ni, P, Cu and O elements. The paramagnetism of Ni-P deposit was gradually transformed into ferromagnetism at 400°C, attributable to the phase separation of Ni and Ni <sub>3</sub> P. The roughness factor, R <sub>a</sub> , of the deposits with P contents ≤12at.% were increased with increasing the annealing temperature at temperatures <400°C but R <sub>a</sub> of the deposits with 17-28at.% of P is approximately independent of the annealing temperature. The rate of hydrogen evolution decreased with increasing the annealing temperature because the specific activity (i/R <sub>a</sub> ) of the Ni-P deposits was decreased with increasing the annealing temperature. © 2002 Elsevier Science B.V. All rights reserved.