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Ni-particles have a ferromagnetic and antioxidation characteristics in general. To prevent the separation of Ni-metal particles from the particulate liquid Ni-metal phases(such as ink etc) should be ultra fine grained. This study shows some results of which Ni-metal particles is chemically reduction precipitated to make ultra-fined particles under the variation of N₂H₄as reduction agent and Na₂C₃H₄ complexant and NaOH solution. 1) Na₂C₄H₄O_6 complexant which is added to depress precipitation of Nickel hydroxide in N₂H₄NaOH solution made rapidly facilitated the Nickel reduction. While inc1eased the Ni-particle size. 2) It was easy to precipitate ferromagnetic Ni-particles with increaseing of N₂H₄quantity in the solution. 3) The specific surface area of Ni-particles was increased N₂H₄agent reduction concentration and temperature of solution. 4) Specific surface area and diameter of fine grained Ni-partic1es obtained at conditions of N₂H₄ 0.6㏖/ℓ, NaOh 7.50㏖/ℓ and 95±5℃ was 38㎡/g, 300 600(A) respectively.

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The structure, saturation magnetization and magnetic anisotropy of Co_(82)Cr_(18) thin film have been investigated. The films were prepared by rf-sputtering technique. The films consist of columnar grains, whose crystal structure is hcp. C-axis of the grains is aligned roughly parallel to the normal of film surface. Angular distribution of the c-axis is less than 6˚ with respect to the normal of the film surface. The saturation magnetization of film is 380 emu/㎤ at room temperature, and it increases about 20 emu/㎤ after heat treating at 400℃ for 1 hour. The easy axis of magnetization of the film is the normal direction of the film. The coefficients of magnetic of the film is the normal direction of the film. The coefficients of magnetic anisotrouty, K_(2θ) and K_(4θ) were 4.9×10＾5 erg/㎤ and -5×10⁴erg/㎤, respectively. The magnitudes of the coefficient increase about 1.7 times by heat treatment at 400℃ for 1 hour.

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Thin film of 18,20 and 25at%Ni-Co were prepared by vacuum evaporation technique. The composition and structure of the film and the resulting magnetic properties such as saturation magnetization, magnetic anisotropy and coercive force, have been studied systematically. The microstructure of the films is a mixture of hcp and fcc phases. The saturation magnetization and coefficients of magnetic anisotropy K_(2θ) and K_(46) decr ease with Ni content, while the coercive force increases. The easy axis of magnetization of thin films is parallel to the surface of films. The coercive force strongly depends on the thickness of films, and reaches maximum value at the thickness of about 0.18㎛. The coercive force increases when the films are held at 300℃ for an hour. However, the saturation magnetization is not changed by the heat treatment.

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The Portevin Le Chatelier effect and anneal hardening of cartridge brass sheets were investigated with expectation of finding a possinble correlation between the two phenomena. The Portevin Le Chatelier effect could be observed when a specimen was rolled less than about 20 pct. reduction, whereas measurable anneal hardening was observed in sheets rolled more than about 20 pct. reduction. About 20 pct. rolling reduction was, therefore, the interested strain range where the two phenomena could be effectively studied together. From sheets subjected to more than 20 pct. rolling reduction, maximum hardness was observed after annealing at 250℃ for ten minutes. When the same annealing treatment was applied to a 20 pct. rolled sheet specimen, its stress-strain curve showed the maximum value of stress fluctuation, Δσ. The result was attributed to the fact that the Portevin Le Chatelier effect and anneal hardening are associated with dislocation pinning by solaute atoms

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Extraction of gallium and germanium has been investigated from a complex ore with sulfuric acid-sodium thiosulfate leachants. The order of reaction as well as the overall reaction rate constant was with respect to sulfuric acid concentration, calculated. Furtheremore, the apparent activation energy and the frequency factor for gallium and germanium were calculated to be A= 1.08min^(-1)., ΔEa=4.5㎉/㏖ and A= 1.01min^(-1)., 5.2㎉/㏖, respectively. Stirring speed has no effect on the extraction rate, which suggested that this profess was chemically controlled. The influence of sodium thiosulfate on the extraction rate was found to be little significant. The rate of extraction increases with increasing temperature and decreases with increasing pulp density. Gallium and germanium extractions were realized approximately as high as 99%, and 70%, respectively.

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A Cu-6Al-2Ni tricrystal was rolled to 20 % of thickness reduction. The lattice orientation was determined by means of the mutual angles of the slip traces produced by microhardness indentation, at one site of each crystal before rolling, and at two, after rolling, respectively at interior of the crystals and near grain boundary regions. All sites are near the triple point of the tricrystal. From this double determination of the crystals orientation after rolling, inhomogeneous lattice rotation of the crystals is observed. The experimental lattice orientation changes are compared with the prediction of the FC, RC models. Those of two crystals are in good agreement with the prediction, while those of the third crystal, which is smaller than the other two and surrounded by them, are in disagreement. From this disagreement, together with a slip line system observed in a microstructural examination at the triple point region, which is in contradiction with the FC, RC models, it is concluded that these simplified models, although remarkable in their ability to predict lattice relations in certain cases, are not applicable to regions of high strain accommodation such as the triple grain boundary region or to grains of small size such as exist in ordinary polycrystalline metallic materials.

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The enthalpy relaxation phenomenon for metal-metal type Fe-Co-Zr(Hf) amorphous alloys has been studied calorimetrically. The magnitude of the exothermic reaction resulted from the irreversible enthalpy relaxation in amorphous (Fe_(1-x)Co_x)_(90) Zr_(10) (x=0-1) alloys was the largest at x=0.5 The changes in ΔC_p(exo) with temperature for amorphous (Fe_(0.5)Co_(0.5))_(90)Zr_(10) and (Fe_(0.5)Co_(0.5))_(90) Hf_(10) alloys showed two stages, a low-temperature one which shows a peak at about 525K and a high-temperature one which shows a peak near Tx. The low-temperature reaction was ascribed to the rearrangement between Fe and Co atoms with weak bonding nature and the high-temperature one to the rearrangement between Fe, Co and Zr, Hf atoms with strong bonding nature. And it was noticed that the high-temperature relaxation causes the decrease in Curie temperature for amorphous Fe-Co-Zr alloys.

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To optimize the alloy design and material performances of the thermoelectric materials with the function of energy conversion of thermal↔electrical, the thermoelectric properties of the V_B Tellurides solid solution compounds have been studied in connection with the single crystal growing, crystallographics and the effects of the alloy compositions and temperatures on the semiconductive properties. The P-N couple performances have been also evaluated in view of application for the direct energy conversion devices.

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Single crystal growth of pure aluminum was studied by using upward continuous casting process. In the present study, a ceramic mold without using a heater was used. Heterogeneous nucleation at the mold wall could be inhibited during solidification by keeping the liquid slightly above the melting point of the metal. Three process variables, i.e. mold temperature, pulling speed and cooling condition, were analysed in terms of their effects on crystal growth. Single crystal was produced by repeated necking. Single crystal could be also produced by making a single necking with a relatively long necking period. By using the new continuous casting process, single crystal of unlimited length could be produced with excellent diameter control and surface smoothness.

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For the investigation of the mechanism of the yield point suppression behavior of pure iron due to electrolytically charged hydrogen, tensile tests of the pure iron specimens were conducted at the temperature and strain rate in the ranges of 285∼318 K and 3.3 ×10＾(-5)∼3.3×10^(-2), respectively. To charge hydrogen into the specimen the current density was maintained in the range of 10∼300A/㎡. Stress relaxation tests and density measurement were also conducted with or without hydrogen changing. Specimen density was measured to be significantly reduced after hydrogen charging. In the case of hydrogen charged specimen, almost all the stress was relaxed, on the other hand, for the specimen without hydrogen the relaxed stress was very small. Yield point phenomenon was disappeared and the yield stress was significant1y reduced by the charged hydrogen. All the experimental results imply that the charged hydrogen forms cavities and these cavities expand in size by the tensile stress. Since there are quite a few number of cavities formed by the hydrogen, at the beginning of the tensile, all the cavities begin to expand to en-large the specimen length. At this stage the specimen begin deform around the cavities which are uniformly distributed. Therefore, one may see the reduced yield stress and may not observe the yield point phenomenon.

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