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The effect of Cr element and heat treatment on the physical and magnetic properties of Fe_(80)B_(12)Si_8 (at.%) amorphous alloy which has a high saturation magnetization and a low core loss was investigated in this study. The (Fe_(1-x)Cr_x)_(80)B_(12)Si_8 (x= 0-0.10) amorphous allay ribbons were fabricated by single roller method and annealed for 20 minutes at various temperatures below the crystallization temperature in Ar gas atmosphere. With increasing Cr contents, it was found that crystallization temperature increased from 472℃ to 490℃ and soft magnetic properties were improved. The coercive force decreased and the maximum permeability increased with increasing Cr contents. These improvements may be attributed to the decreasing of magnetostriction by Cr addition to Fe_(80)B_(12)Si_8 alloy. The annealing treatment improved the soft magnetic properties of Fe_(1-x)Cr_x)_(80)B_(12)Si_8 amorphous alloys and the optimum annealing temperature was 60℃ lower than the crystallization temperature. Coercive force and high frequency magnetic properties of (Fe_(0.96)Cr_(0.04))_(80)B_(12)Si_8 amorphous alloy that was annealed at 425℃ for 20 minutes were comparable to a zero magnetostrictive Co-based alloy.

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Sintering behavior of iron compacts with 2.5 wt.% of(Sn, Cu) additives has been investigated, and the results were compared with those of Fe compact and Fe-4.0 wt.% Cu compact. In this work, the effects of sintering temperature, composition of Sn-Cu additive and admixing method of the additives on dimensional change, formation of interconnecting porosity and radial crushing strength were experiementally studied. The Fe-2.5 wt.% (Sn, Cu) compacts sintered at 890℃ showed better properties for porous bearing application than any of the Fe compact and the Fe-4.5 wt.% Cu compact sintered at 1150℃. Specimen admixed with (Sn, Cu) additive whose Sn/Cu ratio of 35/65 showed highest radial crushing strength, and admixing methods did not show any noticable differences in the strength. Sintering process during heating was studied by analyzing room temperature microstructures with EPMA and X-ray diffraction and the role of the additives in this system was discussed in detail.

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Calcination-Segregation-Magnetic Separation process was attempted to receover the nickel concentrate for lateritic ores. The application of segregation process to the treatment of the calcined silicate and oxide minerals has involved the admixing of these minerals with calcium chloride and ferro coke followed by magnetic separation. Iron oxide additions significantly increased the recovery of nickel with high nickel content concentrate. At the optimum process conditions, and nickel concentrate was obtained with the recovery of about 80% and the concentrate of about 53% Ni content.

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The rotary bending and the tension-compression fatigue tests were performed on as-cast spheroidal graphite cast iron as well as heat treated spheroidal graphite cast irons with three different matrices: ferritic, pearlitic and ferrite-pearlitic. The fatigue limit of the ferrite-pearlitic specimen was higher than that of the pearlitic or the ferritic specimen. It was shown that the fatigue limit was affected by the matrix structures as well as the static strength. The stress intensity factor K, was higher than the notch factor K, in the ferritic specimen. The sensitivity to K of the ferritic spheroidal graphite cast iron was higher than that of the steel with the same tensile strength. The result was attributed to the notch effect of graphite nodules in the matrix

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Effects of temperature, oxygen partial pressure and the addition of impurities, such as Sb and in on the oxidation rare of liquid lead were investigated to provide fundamental data in the dressing stage of pyrometallurgical refinning of lead. In this study temperature and oxygen partial pressure were in the range of 700 to 850℃ and 0.2 to 0.8 atm, respectively. The results showed that the oxidation rate of liquid head was found to follow the parabolic rate law, and that the oxidation rate was increased with increasing temperature, oxygen partial pressure, and also impurity content. The activation energy was for found to be about 39 ㎉/mole for the oxidation of liquid lead.

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Copper clad high carbon steel rods have been fabricated by brazing with a brass filler metal. A rapid heating was needed to prevent dezincification which raised the melting temperature of the brass filler metal. The bonding strength increased with heating temperature within the experimental range between 900 and 980℃. There existed the optimum hearting time and brass foil thickness to achieve the best bonding at a given temperature. The results were discussed in terms of the void formation and grain growth in the brass layer, and the capillary flow of liquid brass.

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In this study, the thermal stability and magnetic properties of Fe_(80)B_(20-x)Si_x amorphous alloys (0
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