This study investigated electrodeposition of Ni-Al（OH）₃ composite films from a Watts type bath containing Al³⁺ and NO₃⁻. Because of NO₃⁻ reduction during nickel electrodeposition, the solution pH near the cathode increases. Then hydrolysis of Al³⁺ proceeds. Scanning electron microscopy（SEM）was used to characterize the composite surface. The aluminum hydroxide produced by the hydrolysis of Al³⁺ was estimated using energy dispersive X-ray spectrometry（EDX）. Surface roughness of the deposits was measured using a three-dimensional surface profiler. Also, results obtained using X-ray diffractometry（XRD）and electron backscatter diffractometry（EBSD）revealed that the preferred crystallographic orientation of nickel changed from the ［100］ direction to ［110］ because of the aluminum hydroxide particles. By increasing the Al³⁺ concentration to 5.0×10³ mol dm³, the deposit surface became smooth and the crystal size was found to decrease. Moreover the Vickers hardness increased in comparison to that obtained from an Al³⁺ free bath. These phenomena are regarded as strengthening effects related to grain size reduction.

Using a plating solution containing CoSO₄•7H₂O, NaCl and H₃BO₃, direct current electrolysis (DC), pulsed current electrolysis (PC), and periodic reverse current electrolysis (PR) were used for cobalt deposition. DC increased in the range of －0.1 A/dm² to －10 A/dm². The minimum internal strain was 62×10⁶ under －2.0 A/dm². For PC, the internal strain was 62×10⁶ to 84×10⁶. For PR, the internal strain was 26×10⁶ to 29×10⁶, which was less than that of either DC or PC. It changed cyclically from tensile strain during deposition to relaxation during anodic dissolution of cobalt deposits. The surface morphology was investigated using scanning electron microscopy. Fine grain surfaces were observed in DC and PC. For PR, the surface morphology influenced the poorly defined hexagonal Co crystal. The X-ray diffraction pattern of the cobalt deposits can be obtained under both DC and PC. Both fcc {110} and hcp {11•0} structural planes were investigated during deposition. Especially, the fcc was formed originally. Then the fcc transformed drastically into the hcp. These grains spontaneously relaxed desorption of hydrogen with cobalt produced by the hydrogenated deposits. However, using PR, the hcp was different {10•0}, {10•1}, and {10•3} planes.

The plating film texture and hardness obtained from a nickel citrate solution using pulse electrolysis were investigated. The duty ratio effect on hardness was found to differ depending on the T_on time. Results show that the I_av influence on hardness was greater for low I_av. A Hole-Petch relation was found to exist between the hardness and crystal grain size.