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The magnetic properties of amorphous Fe_(80-x)Co_xSi_6B_(14)(10≤X≤70, X ; 10at% interval) and Fe_(80-x)Co_xSi_9B_9P₂(10≤X≤70, X, 15 at% interval) have been investigated. The amorphous alloys were fabricated into ribbons by a single-roller rapid quenching technique. The saturation magnetization and its temperature-dependence, coercive force and power loss were studied. The saturation magnetization of the amorphous Fe_(80-x)Co_xSi_9B_9P₂alloy shows similar tendency to that of amorphous Fe_(80-x)Co_xSi_6B_(14) alloy except Fe-rich composition at room temperature. The average effective magnetic moment per transition metal atom in both alloys is 2.10-141 μ_B, and decreases with Co content, but increases slightly with Co content from X=40. The coercive force and power loss are 0.31-0.11 Oe and 33-49 mW/Kg at 0.5 Tesla and 60 Hz, respectively, and decrease with Co content.

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A mathematical model was proposed for the case in which reactants diffuse out through the oxide product layer and react with oxygen on the surface. This model was derived on the basis of intra and intergranular diffusion in series, also combined with structural parameters such as porosity, grain size and the effective diffusion coefficient of the gas. The rate of oxidation of nickel which forms the P-type oxide, was measured at elevated temperatures. The rate increased with increasing porosity, reaction temperature and also oxygen partial pressure. The computer simulation of the model under the given boundary conditions were found to be in fairly good agreement with experimental results, thereby elucidation the oxidation mechanism. The diffusion coefficient for the intragrnular diffusion process were determined to be 5.0×10＾(-8)㎠/sec and 1.0×10＾(-7)㎠/sec at temperature of 920℃ and 970℃, respectively.

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Wetting phenomena and interfacial reaction ,,』 Al-2 at7(Cu,Mg,Si) alloys to the SiC, B₄C particulates and SiC whiskers were studied through pressurized infiltration experiments. Four major variables studied for the wetting phenomena in ceramic/aluminum alloy systems are alloying element, gas pressure, holding time and melt temperature. Infiltration distance vs gas pressure and interfacial reactions were investigated with optical microscopy, SEM, WDS, EHS and fractography. Infiltration behavior of aluminum alloy to the ceramic showed some discrepancies from the theoretical behavior calculated with thermodynamic data. The threshold infiltration pressure decreased for all the ceramic/aluminum alloy systems as the temperature and holding time increased. The effect of alloying element on decreasing the threshold infiltration pressure was most profound in the case of Mg addition. A correlation between interfacial reaction and wettability was also found.

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The tensile deformation behavior of copper, brass, nickel silver, phosphorous bronze and cold rolled steel sheets were studied. Based on true stress-true strain curves obtained by the uniaxial tension test at a constant cross-head speed, several constitutive equations were determined utilizing the regression analysis, and applicability of these equations to describe the stress-strain behavior of the non-ferrous alloys was investigated. In the present study, a Modified Voce equation, σ= B - (B - A) exp(-nε-C) is suggested, where a new term "C" has been incorporated into the exponential term of the Voce equation. The Modified Voce equation fits best with the experimental data of the nonferrous alloys and cold rolled steel sheets tested. From detail analysis of the exponential term, the value of "C/n" is found to be equal to the amonunt of pre-strain.

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Dual-phase steels with different phase ratios were produced by water quenching from different intercritical temperature of 740℃ and 780℃. The steels were then cold rolled and aged at 600℃. Tensile properties were not much different in spite of the different phase ratio. the aging treatment increased the strength and decreased the elongation of the steels studied. Cold working and aging treatment promoted delamination. Carbide precipitate on grain boundaries, which have been produced by the aging, affected the delamination most strongly.

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Thermal stability of rapidly solidified Al-Fe-Cr alloys was examined. Structural change during consolidation was monitored and the structural stability of the extrudate was assessed. The microstructure of rapidly solidified Al-Fe-Cr alloys was stable up to 623 K. Above 623 K, supersaturated solid solution decomposed as A1_6Fe at grain boundaries. TEM micrographs of the extruded Al-Fe- Cr alloys showed supersaturated solid solution, finely dispersed particles and recrystallized grains.

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A hot-wall type reactor has been designed for chemical vapor deposition at low pressure(LPCVD), and deposition of W on an oxide patterned Si-wafer has been studied. Utilizing scanning electron microscope and cross-sectional transmission electron microscopy, selective deposition of W only on the exposed Si surface has been confirmed. It has been observed that the microstructure of the W-film is strongly affected by flow rates, i.e., partial pressures of reaction gases(WF_6 H₂ and Ar). Fourpoint probe measurement of the thin film showed that porosity in the LPCVD W-film is one of major causes which increases sheet resistivity of the film, and the quantity of porosity is affected by reaction species and individual flow rates.

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Based on the distribution coefficient of antimony, the activity of SbS_(1.5) in copper-saturated matte has been calculated. The distribution coefficient of antimony between copper and matte phases has been measured at 1400 K and 1500 K. In the copper-saturated Cu₂S-SbS_(1.5) matte, the activity of SbS_(1.5), follows the Henrian behavior at extremely low concentration of SbS_(1.5), while it exhibits negative deviation from the Raoult`s law at the dilute concentration of SbS_(1.5).

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Magnetic measurements on the rapidly solidified(RS) FeAl_(1-x) Co_x series have been made at temperature from 77K up to 800K, and compared with those of the annealed specimens. Annealed alloys with x≤0.20 showed paramagnetism, with x=0.20 and 0.25 superparamagnetism, and with x≥0.30 ferromagnetism. Rapidly solidifed alloys with x≥0.30 showed ferromagnetism and alloys with x≤0.25 remained superparama-gnetism. The rapidly solidified specimens, in general, showed stronger magnetic behaviors than the annealed ones. The alloys of FeAl_(0.70) Co_(0.30), both annealed and rapidly solidified, showed mictomagnetic like properties. X-ray diffraction data revealed that both specimens, rapidly solidified and annealed, were single-phased in B₂(CsCl) structure with virtually constant lattice parameter, 2.91A. The rapidly solidified alloys, exhibited some extent of disorder in the site occupancies of Al atoms and Fe atoms.

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The Enclosed-arc welding simulated at the laboratory level was applied to the rail steel of high carbon Cr-Ti alloy containing 0.1 w/oTi. After welding, the impact toughness and the fatigue properly of the welded zone were investigated in connection with the austenite grain size and microstructure. Also these mechanical properties of the high carbon Cr-Ti alloy rail steel were compared with those of common rail steel. According to the experimental results, the impact toughness and the fatigue property at HAZ, on the whole, increased as the pearlite interlamellar spacing and austenite grain size became finer. And there was little variation in the fatigue property of the welded zone because of the effect of pre-worked notchs at the alloy rail steel. As the cementite spheroidizing phenomena were remarkable at HAZ, both the impact toughness and the fatigue strength increased. Throughout the welded zone of the high carbon Cr-Ti alloy rail steel, austenite grain size showed little variation, and had ASTM No.4.5-5 at a distance of 25㎜ from the bond. The impact and fatigue properties of the high carbon Cr-Ti alloy rail steel were found to be superior to the these of common rail steel.

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