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The magnetic properties of 45% Ni-Fe permalloy sheet was studied by measuring its coercive force(H_c), maximum permeability(μmax.), remanence(B_r), induction at 10 Oe(B_(10)) and texture in order to understand the relationship between magnetic properties and preferred orientation with cold reduction in this alloy. Specimens were prepared by annealing from 900 to 1200℃ for 3 hours under high-pure H₂atmosphere after 60, 70, 80 and 90% single cold rolling. With increasing cold reduction, the {100}$lt;100$gt; texture developed strongly. This texture improved the properties of coercive force and maximum permeability because $lt;100$gt; is easy direction of magnetization in ferrous alloy. The high-temperature annealing in dry H₂improved also coercive force and maximum permeability by reducing impurity and the number of grain boundaries that prevent a movement of magnetic domain wall. B_(10) was not affected by cold reduction and annealing temperature. This means that B_(10) is not affected by texture and grain size in contrast to the coercive force and maximum permeability. B_(10) was 14000 Gauss and B_(50) was 14500 Gauss at room temperature (20℃). Br was not affected by cold reduction but was decreased remarkably by increasing annealing temperature. It is considered that the remanence is affected by impurity and grain size but not by texture.

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Raipdly solidified powders of Ni-6.61%Al-3.35 %Ti-0.019%C and Ni-6.49%Al-1.98%Ti-5.34%Mo-0.028%B-0.33%Fe-0.084%C were investigated ; microstructures of the powders had been investigated at as-rapidly-solidified state and after annealing at 800℃ and 1,000℃. After rapid solidification by Ar gas atomization, the microstructure of the powder particles showed dendritic or equiaxed poly-grain morphology irrespective of the particle size. The elongated γ` phase has been precipitated next to grain boundaries in the direction perpendicular to the grain boundary, and ultrafine γ` particles were dispersed within the grains. When the alloy powders were annealed at 800℃ and 1,000℃, the elongated γ` phase had grown to an irregular shape, and the ultrafine γ` particles inside the grains had grown to a cubic shape.

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The changes of microstructure and fatigue properties by thermonechanical processing have been studied for Ti-6 Al-4 V alloy, A fine lamellar morphology was produced by solution treatment and annealing while a fine equiaxed structure was obtained by the thermonechanical processing at the tem-perature range of α+β phase. The change of morphology of a phase from fine lamellar to equiaxed one was associated with dynamical recrystallization resulting from hot rolling. The fatigue response was enhanced for the fully annealed equiaxed structure compared to that of the mixture for fine lamellar and equiaxed ones. The improvement of the fatigue propenties was attributed to the stabilization and strengthening of βphase which was the site for crack nucleation.

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Research on the extraction of cobalt(II) from sulfate solution by means of liquid surfactant membrane containing D₂EHPA as extractant and SPAN 80 as emulsifier is presented. In this study, it was observed that the extraction rate of cobalt(II) was greatly enhanced by the presence of a sodium acetate and by the increase of pH in the aqueous feed solution. The optimum concentration of D₂EHPA and SPAN 80 in membrane phase were about 5 vol%, 2.5-3.0 vol% respectively. It is also found that the extraction of cobalt ion is promoted as both the Ve/Vw ratio increases and the W/O ratio decreases. But the extraction efficiency of cobalt(II) was reduced with increasing sulfate ions in aqueous feed solution.

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Tensile properties at room and high(100, 200 and 300℃) temperatures were studied for the Al-2.0 wt%Li binary alloy and Al-2.0wt.%Li ternary alloys with the addition of either 1.2 wt%Cu, 1.0 wt%Mg or 0.12 wt%Zr. The tensile and yield strengths of Al-2.0 wt%Li alloy were decreased rapidly with increasing the test temperature above 100℃. The tensile strength at 300℃ of this alloy is less than 6 Kg/㎟. This rapid decrease in strength results from coarsening of δ` phase and precipitation of stable δ phase. The strength of the Al-2.0 wt%Li-1.2wt%Cu alloy were much higher than that of the binary alloy because of the solution and precipitation hardening. The strengths of Al-2.0wt%Li-1.0wt%Mg alloy were higher than those of the binary alloy due to the solid solution hardening and the homogeneous distribution of δ` phase, but lower than those of the Cu-added ternary alloy. The strength of the Al-2.0wt%Li-0.12wt%Zr alloy was slightly higher than those of the binary alloy due to the grain refinement and the precipitation of a composite phase.

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The mechanism of slagline wear which is occurred in flux-metal corrosion line and its adjacent regions of a zirconia graphite submerged nozzles has been investigated. The results can be obtained by the following experimental methods such as the observation of a polarizing microscope, EPMA, X-ray diffractometric techniques and theoretical considerations. Since slag wets and dissolves zirconia in preference to graphite and molten metal wets and dissolves graphite in preference to zirconia, the slag and the metal creeps up and down alternatively to produce local corrosion on the nozzle in contact with slag/metal interface. It was found that the main failure mechanism is that the highly fluid mold flux penetrates into the subgrain boundaries and breaks down the grains into the fine subgrains, which are washed away by the slag. The attack is enhanced by the motion of the slag film induced by the Marangoni effect combined with gas evolution. Another mechanism is that once graphite which holds the ZrO₂ grains together at the hot face is oxidized in contact with slag film, zirconia grains are removed into the slag. The decarburization may be possible by the Na₂O contained in the mold powder and the FeO formed at the slag/metal interface.

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A Numerical study was performed for the two-dimensional turbulent stirring flow created by linear motor in a continuous casting system. A k-εturbulent model was applied to solve time-averaged turbulent momentum equations within the computation domain. Four different situations in a stirring system being consisted of two-dimensional slab of 1 m(width) × 0.2 m(height) have been investigated, that is : Model (A) : W =0.1 m and B_0=0.01 tesla, Model (B) : W =0.3 m and B_0=0.01 tesla, Model (C) : W =0.1 m and B_0=0.02 tesla, Model (D) : W =0.3 m and B_0=0.02 tesla, where W is the length of linear motor and B_0 is the magnetic flux applied on the motor-side-surface of the slab. The results shows that the flow characteristics depends mainly on the magnetude of B_0 not on W. The order of the magnitudes of turbulent intensity at four flow situations were almost same. However, the magnitude of turbulent viscosity became much less in case of greater B_0 than in smaller B_0. Therefore it is recommended that the stirrer with greater B_0 should be used to make finer stirring action.

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Thermomagnetic analysis of rf-sputtered Co_(84)Cr_(16) and Co_(78)Cr_(22) films have shown unusual behavior. In the Co_(78)Cr_(22) films, Ms remains non zero upon heating up to 700℃ but did not appear until around 260 ℃ on cooling. After the one cycle heat treatment Ms of the film at room temperature was close to that of bulk materials of the same composition. This phenomenon is attributed to Cr redistribution from Cr rich column boundary region. On the contrary Co_(84)Cr_(16) films showed increase of Ms value above 600℃ upon heating and this seems to be related to the appearence of a fcc phase which may be rich with Cr. The angular dependency of coercivity has shown that shape anisotropy due to Cr segregation at column boundary is dominant factor for perpendicular anisotropy in as-sputtered Co_(78)Cr_(22) films. Upon heat treating the angular dependency of coercivity was diminished though the C-axis alignment of the film was kept, which indicates Cr redistrbution as has been mentioned.

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ISML-ITMT(Institute Sperimentleder Metalli Leggeri-Intermediate Themomechanical Treatment) increases greatly fracture toughness of 7475 aluminum alloy. The ISML-ITMT samples have shown fine microstructure with small volume fraction of coarse particles, hence small number and large spacings of particles. This distribution of coarse secondary particles contributed to increasing the fracture toughness. The larger the spacing of intermediate particles in ITMT samples is, the higher the toughness is. The dimple spacing of the fractured surfaces was almost the same as the coarse particle spacing, suggesting that the coarse particles act as nucleation sites of micro-voids. Grain refinement does not seem to contribute to increasing the toughness. The most important parameter for increasing the fracture toughness is the distribution of coarse particles rather than the grain size.

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A partial binary phase diagram of the system Na₃AlF_6-NiO was investigated by means of Differential Thermal Analysis (DTA) to obtain informations on the feasibility of utilizing cryolite as a metal refining flux. Meanwhile, the X-ray powder diffraction techniques were employed to indentify solid solubilites near end compositions. The DTA heating rate and the sample weight for the experiment were, 5℃/min and 10 ㎎, respectively. Experimental results thus obtained showed that the system of Na₃AlF_6-NiO is a simple eutectic over the range studied(0-30㏖% NiO) with the eutectic point at 6㏖% NiO and 1236 K.

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