Cobalt, nickel and Co-Ni alloys were electro-deposited with an alternating current on the oxide coatings of aluminum anodized in the sulfuric acid bath. These metals precipitated in the micropores of the oxide films and show characteristic magnetic properties. The films can be applied to magnetic devices for memories and recordings.
The results obtained by the present study are summarized as follows:
(1) Electron microscopic studies revealed that the deposits in the micropores of oxide films were fibrous crystals with a diameter about 100Â and about 0.1-0.5 μm in length.
(2) The metals precipitated densely close to the bottom of the micropores and gradually grew to the surface of the films. The layers of ferro-magnetic metals distribute uniformly almost parallel to the surface of the substrates.
(3) The residual densities of magnetization of cobalt and nickel deposits increased to about 1, 700 and 600 gauss respectively when the outer layers were lapped to a few microns in thickness.

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Reaction-diffusion of the Al-Ag system was investigated by the electron probe micro-analysis. Experimental results obtained were as follows.
(1) Intermediate phases ζ and μ were formed by the diffUsion between aluminum and silver.
(2) Thickness of the ζ phase was expressed by the equation of W=k√t, where t was the diffusion time and k the growth rate constant. And the k was expressed as follows.
k²₁=3.1×10^-1exp(-28000/RT)cm²/sec (360°C440°C: ζandμphases)
k²₂=6.6×10^-1exp(-29000/RT)cm²/sec (480°C560°C: onlyζphase)
k²₃=2.6×10^-1exp(-28000/RT)cm²/sec (360°C560°C: all temperature range measured).
(3) Interdiffusion coefficients in the ζ phase were expressed as follows.
D₁=2.1×10^-1exp(-27000/RT)cm²/sec (360°C440°C: ζandμphases)
D₂=2.1×10^-1exp(-27000/RT)cm²/sec (480°C560°C: onlyζphase)
D₃=2.5×10^<-1>exp(-27000/RT)cm²/sec (360°C560°C: all temperature range measured).
(4) It was shown by the Kirkendal effect that aluminum diffused faster than silver.

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The influence of heat treatment, microstructure, corrosion rate and electrode potential on stress corrosion cracking of 5083 aluminum alloy has been studied in various sodium chloride solutions.
The results obtained are as follows:
(1) In a specimen heated for 1 week at 80200°C, stress corrosion cracking occurs with a maximum susceptibility at 180°C, but in specimens heated, above or below this temperature it hardly occurs.
(2) Stress corrosion cracking is in a close correlation with intergranular corrosion. Grain boundaries with continuous β precipitates provide an effective path for cracking.
(3) It is shown that the susceptibility to stress corrosion cracking is evaluated from the change of the natural electrode potential with time in 57g NaCl/L+10cc H₂O₂ (30%)/L solution.
(4) The mean crack propagation rate is expressed as an exponential function of the corrosion rate.
(5) The cracking susceptibility increases remarkably with anodic polarization and decreases with cathodic polarization at slightly negative potentials from the natural electrode potential.
(6) The contribution of mechanical rupture is found in the process of cracking. The crack propagation, however, may be essentially caused by localized mechano-chemical dissolution at grain boundaries.

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For the growth of intermediate phase layers formed in a poly-phase diffusion zone, the equation in which the rate constants of phase growth are expressed as functions of the interdiffusion coefficients and the boundary concentrations of each phase was derived by modifying Heumann's method.
The purpose of this study was to elucidate the factors controlling the layer growth of intermediate phases phenomenologically.
The simulation by using the above equation show that the relative magnitude of the rate constant of phase growth in a poly-phase diffusion zone was related to the relative values of D×ΔC in each phase. It is also concluded that the rate constant of the total width of a diffusion zone is controlled by the value of nΣi=1(Di×ΔCi). Therefore if the value of D×ΔC in each phase is known, the total width of a diffusion zone could be quantitatively predicted.

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