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The effect of Mn and Ti on the mechanical properties, the transformation temperature and the shape memory effect of a Cu-Al-Ni alloy have been studied . Addition of 0.35∼0.89wt% Ti and/or 1.67∼1.81wt% Mn reduced gram size of the alloy by a factor of 2, to 50∼70㎛. The fracture stress and strain of the alloy with Ti and/or Mn were 2 times as great as those of the alloy without addition. More Ti beyond solubility limit in the alloy have not a great effect on mechanical properties, shape memory effect and transformation temperature with aging time at 200 ℃. In hyper eutectic Cu-Al-Ni alloy, treansformation temperature is increased slowly without decrese in shape memory affect with aging time at 200℃. In hypo eutectic alloy, on the other hand, transformation temperature is decreased with decrease in shape memory effect after aging time of about 3 ×10＾5 sec at 200℃.

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The intrinsic kinetics parameters for the hydrogen reduction of copper sulfate have been determined from experimental data obtained under linearly increasing temperature. Various different mathematical procedures have been applied to the analysis of the data. The kinetics of this reaction can be described by an overall first-order expression in terms of the amount of unreacted copper sulfate with an activation energy of 75.4kJ/㏖. In comparison to the isothermal method, the nonisothermal technique is shown to be quite convenient and require fewer experimental runs for the determination of intrinsic kinetics.

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To study the effect of silicon additions on the boronized depth, hardness and wear of the boronized layer, an electro-boronizing on the substrate such as electrolytic iron, ferritic and austenitic stainless steel has been carried out at the current density of 0.5A/㎠ and in the temperature range of 800-1000℃ for 1-5 hours. the findings from the experiment are summarized as follows. 1) Increased boronize depth was obtained with increased addition of silicon. excess silicon addition, however, inhibited the buronizing due to the increased viscosity of electrolyte. 2) Deeper boronized layer was resulted with ferritic than austenitic stainless steel. the boronized depth of the both stainless steels, however, were only one-third that of the electrolytic iron. 3) Wear resistance of the substrates was improved markedly by boronizing, showing the best result in the ferritic followed by austenitic stain-less steel and electrolytic iron.

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The rapidly solidified structures of Fe-C binary alloy containing 3.8-4.5 wt%C made by using the melt spinner and gas atomizer was analyzed and how the solidified structure of it, of which consolidation temperature is expected to be 700-1000 ˚C, changed was considered. As a result of experiment, the solidified structure consist of the eutectic structure of austenite and cementite, the size of which was within sevaral ㎛, and at the last solidified part, the austenite dendrite was observed. In the solidified structures by using the melt spinner, any meta-stable phase was not observed, but in the powder under the 25㎛ solidified by using the gas atomizer, there much observed meta-stable ε-phase. The microhardness of it showed the initial value of 550-900MVH(㎏/㎟) and even though after annealing. The high value of 700-800MVH(㎏/㎟) was also measured. So, it is possible that these metarials have practical use.

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Effect of aging condition on the microstructure and hardness properties of Al-3Li, Al-3L₁-2Cu, Al-3Li-2Cu-0.3Zr have bean studied. The alloy ribbons have been prepared by means of Single Roll Melt Spinning by rapid solidification technique. In rapidly solidified Al-3Li-2Cu, Al-3Li-2Cu-0.3Zr alloy ribbons show the icosahedral intermetallic compound of five-fold symmetry which is placed in cell-boundary and matrix. In the matrix precipitated fine δ(Al₃Li) phase. Heat-treated at 250 ℃ 1hr. In this condition, δ`(Al₃Li) phase started decompose. The icosahedral intermetallic compound has been grown. When heat-treated at 300 ℃ 1hr, the δ(Al₃Li) phase has been decomposed all. In the matrix, icosahedral intermetallic compound has been grown greatly. The micro-hardness has been obtained in more high Al-Li-Cu-(Zr) alloy than Al-Li alloy. Strength-hardened phenomena showed solution hardening by the addition of Cu. When the heat-treated at 250 ℃ 1hr, in the alloy of Zr addition, delayed decomposed δ` phase. In the case, micro-hardness gradually decreased. When the heat-treatment have done at 300 ℃ 1hr, the micro-hardness has been decreased because δ` phase decomposed all.

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The oxides of tungsten, iron, chromium are very strong carbide forming elements, therefore, it is a very useful method that their oxides are reduced by carbothermic In- Flight Plasma reduction. The experimental apparatus in the present study used a secondary nozzle and an electromagnet so that the plasma flame could rotate in the secondary nozzle. The variables of experiment were the amount and the sort of the reductants, size of feeding materials and the powder feeding rate. The reduced particles were collected in water cooled pipe and paper filter. By increasing the reductant ratio and the reduction ratio the fixed carbon content and free carbon content were increased. By increasing the powder feeding rate and the size of feeding material the reduction rates were decreased. The reduction rate of WO_(2.9) Fe₂O₃and Cr₂O₃were 80%, 90% and 20%, respectively, by the in-flight plasma process. The reduced particle size were below 0.03㎛ ; therefore, an ultra-fine powder could be obtained by the present in-flight plasma process.

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Solid-state electrochemical measurements were made to determine diffusivities and thermodynamic functions of oxygen in Ni and Pd. Diffusion of oxygen was caused by applying preselected potentials between the reference and specimen electrodes and was monitored by measuring time-dependent potentials and or currents. The following results were obtained for the diffusivities and terminal solubilities of oxygen in solid Ni and Pd : (수식) The thermodynamic properties of the Ni-O and Pd-O solutions follow the general tendency of periodic behavior from group to group.

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This study is concerned with the investigation of wear properties of commercial rail steel and high carbon Cr-Ti a1loy steel which is expected to be the new prosperous and energy-saving rail steel. Especially, using rolling contact fatigue test method, the running surface layer of alloy steel and its wear surface were investigated by metallography in detail, in order to clarify the wear behavior of alloy steel. Experimental results showed that the amount of wear of high carbon Cr-Ti alloy steel was half as much as the commercial rail steel. Through the SEM observation of running surface layer, the wear behavior of alloy steel proved to be related to the strain hardening occurring under the wear surface and to voids and microcracks generated in those strain hardened areas as sliding distance increased. The shape of wear debris of this alloy steel showed shallow-rounded sheets. During rolling contact fatigue test, the fatigue cracks of alloy steel were observed as flake type and she11ing damage defects. It has also been thought that those phenomena of alloy steel resulted from pearlite lamella structure of pearlitic steel.

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The effects of roll gimp and characteristics of copper powders on powder strip compaction by a normal two-high mill have been investigated. Sintering of the green strip and rolling of the sintered strip have also been studied. The density of the green strip increased almost linear1y with decreasing roll gap. The higher green density did not necessarily yield the better results, because too much densification caused inhomogenity in density and hydrogen blisters in sintered strips. The optimum relative density of the green strips male of electrolytic copper powders was found to be 70 to 80 percent. The shrinkage of the green strip during sintering varied with directions. The shrinkage was highest in the width direction, intermediate in the rolling direction and lowest in the thickness direction. Heavy cold reductions of the sintered strips gave rise to complete densification and textures which are similar to those of conventional cold rolled copper sheet.

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The hardenability and mechanical properties of Low-carbon steels containing Cr were investigated and the results were correlated with Cr content. The hardenability decreased with increasing the austenitizing temperature and increased with Cr content. But the hardness was increased slightly by dereasing the tempering temperature and increasing Cr content. And the softening of boron steels by adding Cr was delayed during tempering. There was one step embrittlement in notch toughness test, the thin and long particles precipitated along the lath boundary may be a major factor. The tensile properties were improved by adding Cr. Impat energy increased when tempered at higher temperatures, hut tensile strength and yield strength decreased continously with tempering temperature.

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