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The structures, the mechanical properties, the high temperature oxidation and sulfidation behavior of the unidirectionally solidified Ni₃Al (γ`)-Ni₃Nb(δ) eutectic alloy were investigated. Casted eutectic alloy round bar was directionally solidified with rates (R) between 0.6㎝/ hr and 12㎝/hr at induction furnace maintaining the thermal gradient (G) at solidliquid interface, 130℃/㎝. The eutectic microstructure was varied according to the growth condition (G/R ratio). When G/R ratio was larger than 130℃·hr/㎠ the lamellar structure was formed, and the colony structure was formed, when G/R ratio was smaller than 130℃·hr/㎠. It was found that the interlamellar spacing (λ) was dependent on the growth rate (R) through the relationship, λ²·R=8.4×10^(-13) ㎤/sec. The results also indicated that high temperature strength in tension to the growth direction of Ni₃Al-Ni₃Nb eutectic alloy was better than that of the known conventionally tasted nickel base superalloy B-1900. The microhardness of this eutectic alloy increased with the growth rate increase. The high temperature oxidation in static air of this eutectic alloy was occurred paraborically. The activation energy of parabolic process was 21 ㎉/㏖. High temperature oxidation was accelerated by the presence of Na₂SO₄.

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An experimental study has been made to determine tensile properties and forming limit curves for a variety of permeable nickel-iron alloys whose nickel contents ranged from 34 to 82 percents. The values of tensile strength, yield strength and elongation of the alloys indicated that the alloys have good formability. The true uniform strains of the alloys were about 0.3 which is larger than that of low carbon steel and lower than brass. The relative cup height (Hf/Dp) was increased with increasing lubrication and also increasing strain rate sensitivity for the same true uniform strains. Forming limit curves of the alloys were at similar levels as those of low carbon steels.

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The reduction of some transition metal sulfate, such as Ag₂SO, CuSO, NiSO₄, CoSO, FeSO, MnSO, etc., by hydrogen had been studied over a range of 0.2 to 1.0 atm in hydrogen partial pressure. 1) The beginning temperature of reduction was found to be directly proportional to the standard free energy(G) of formation of sulfates. T(°K)=-4.71G-223.8 2) Reduction solid products of sulfates by hydrogen may lead to the following one, (l) metal, (2) sulfide, (3) mixture of sulfide and metal. 3) Reaction rate were fitted to da/dt＝kf(a)P_(H₂) And the rate of reduction was found to be directly proportional to the hydrogen partial pressure in some range. 4) The apparent activation energy for the reduction is found to be 22.1㎉/㏖ for CuSO₄, 23.5㎉/㏖ for NiSO₄, 18.1㎉/㏖ for CoSO₄, 33.2 ㎉/㏖ for Ag₂SO, respectively.

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A study has been performed on the effect of Thermomechanical Treatment on the toughness of 7075 Aluminum alloy. Three different heat treatments such as Intermediate Thermomechanical Treatment (ITMT), Thermomechanical Treatment (TMT-2) and Conventional Heat Treatment have been applied in this study. The experimental results showed that the ductility and the toughness were increased by ITMT and TMT-2 compared with Conventional Heat Treatment, It was believed that the increase of ductility was due to grain size refinement, and that the toughness increased was due to grain size refinement, retardation of the recrystallization and homogeneous distribution of small Cr-rich particles.

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Morphology, dependence of prior austenite grain size and packet size upon austenitizing temperature, distribution of lath width, and habit plane of martensitic structure in Fe-4Cr-0.4C steel has been studied by optical microscopy and transmission electron microscopy. The results obtained are as follows. 1) Optical microstructures of martensitic Fe-4Cr-0.4C steel consist of lath martensite and lens martensite. Also the four types of morphology are observed by electron microscopy. The most common morphologies are a regular paralleled martensite and an irregular dovetailed lath martensite, while the remainder of microstructures consists mainly of groups of internally twinned martensite and autotempered laths. 2) Prior austenite grain size and packet size, increased with austenizing temperature, and also the numbers of lath contained in a prior austenite grain or a packet are increased with austenizing temperature. 3) The mean width of lath in Fe-4Cr-0.4C steel is about 0. 23㎛ and most of lath widths are below 0.5㎛. 4) Martensite habit plane of Fe-4Cr-0.4C steel is nearly {110}α`

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Spheroidization of cementite in eutectoid steel by concurrent warm torsional deformation has been studied with emphasis of the effects of the strain rate and the inter-lamellar spacing. Complete spheroidization could be achieved in 3 minutes when the strain rate and the deformation temperature were 1.76 percent/sec 700℃ respectively. The rate of the sphsroidization increased with increasing temperature at a given strain rate and lameller spacing. The coarse pearlite was more easily spheroidizad than the fine pearlite when other conditions were same.

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