The computer simulation program concerned with the continuous casting of 0.5m diameter 6063 aluminum billet was completed using the steady-state difference method proposed by Adenis et al. From the measured isotherm profiles it was concluded that the ingot had not reached the steady-state in the initial 2m. In order to simulate the temperature distributions of these non-steady-state ingots using the same program, experimental formulas were proposed using the apparent thermal conductivity in the solid phase, taking the initial strong cooling effects into consideration. Three experimental results were obtained with casting velocity 0.75m/s: the thermocouple heads were inserted when the billet length was 0.6m (run a), 1.0m (run b) and 1.2m (run c), respectively. Corresponding to these experiments the following K equations were selected.
run a: K=175+586×t^-1/2
run b: K=251-100×10^-3t
run c: K=230-75.3×10^-3t
In run a, the heat transfer coefficient from the high temperature region of the billet surface to the cooling water was also improved to obtain good agreement with experimental data.

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A relation between resistivity at 77K (ρ₇₇) and resistance ratio (R_??_ρ₃₀₀/ρ₇₇), induced from Matthiessen's Rule and empirically determined in commercial pure aluminium, was applied to Al-10%Fe powder extrusions degassed and extruded at 573K after N₂ gas atomization and classification. ρ_M77 and Matthiessen size factor (M.F.=ρ_M77/Ω₇₇ where Ω₇₇ is resistance measured at 77K) were calculated from the R. Dependences of the ρ_M77 and the M.F. on average powder diameter and their change by isochronal heat treatments were investigated. It was considered from ρ_M77 that, even after the extrusion at 573K, solute Fe concentration was higher than maximum equilibrium solubility. Ratio of the M.F. to usual geometrical size factor (G.F.), M.F/G.F., was small in specimens of small average powder diameter. The M.F./G.F. decreased with decrease of the ρ_M77 due to precipitation of Fe in low temperature treatments, then increased before or with increase of the ρ_M77 due to re-solution of precipitates containing Fe at higher temperatures. In many cases of treatments, increase in the M.F./G.F. corresponded with the softening. Specmens of smaller powder diameter showed softening at lower temperatures. However, even in specimen of the smallest powder diameter, 36μm, almost no softening occured at 573K. Specimens of powder diameter larger than 108μm maintained their as-extruded hardness after holding for 600ks at 623K.

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Although fiber arrangement in preforms does not affect the interfacial energies nor contact angle in a given composite system, it affects the threshold pressure of infiltration into fiber preforms remarkably. The processing parameters, such as pressurizing rate, pressure holding at the maximum applied pressure and molten metal temperature, affect the apparent wettability, consequently they also affect the threshold pressure. In this study, δ-alumina fiber/molten aluminum composite system was selected to in vestigate the influence of such processing parameters on the threshold pressure of infiltration. Pressurizing rate in infiltrations was changed from 0.20kPa/s to 16kPa/s, pressure holding at the maximum applied pressure for 300s was also performed. The pressurizing rate and pressure holding at the maximum applied pressure do not affect the threshold pressure into alumina fiber preforms with quasi-planar random arrangement. It is experimentally approved that the threshold pressure obtained by extrapolation of infiltration distance and applied pressure agrees with the one obtained by the pressure drop based on Blake-Kozeny's equation. The influence of molten aluminum temperature on the threshold pressure which was obtained by the pressure drop, was studied with the pressurizing rate of 2.4kPa/s. The threshold pressure decreases from 259kPa to 162kPa with molten aluminum temperature increased in the range of 943K and 1163K.

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Statistical examinations were done for the SCC resistance of conventionally treated and RRA-treated 7475 aluminum alloy sheets. The SCC lives of RRA-treated specimens vary widely, and the minimum levels of lives of RRA specimens, in the case of RRA condition with keeping the T6 strength level, are close to that of T6 specimens. And also, additional treatments such as pre-agings at low or high temperatures and repetition of retrogression and reaging produce insignificant improvement of SCC lives. Consequently, an RRA-condition aiming at no lowering of the T6 strength has no practical importance. On the other hand, considerable improvement of SCC resistance with high statistical reliability is obtained for the specimens treated by the RRA condition containing an over-aging retrogression process, though a certain extent of strength loss is unavoidable. Therefore, only an RRA condition containing an over aging retrogression process should be adopted in practice for at least 7475 aluminum alloy.

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The effect of tin addition in aluminum on the diffusion weldability of copper and aluminum has been investigated. The welding was carried out at 773K for 1.8ks, 3.6ks, 7.2ks and 14.4ks under the pressure of about 2.0MPa in a vacuum of 0.1Pa. Tin plays an important role in destroying the aluminum oxide layer, relaxing thermal stress and also in diffusion of the alloying elements (Mg, Zn, In, Bi) to the welding interface. High joint strength is obtained by addition of tin. The dual addition of tin and magnesium to aluminum brings about a joint, the shear strength of which is higher than that obtained by the single addition of tin. Such intermetallic compounds as γ₂(Al₄Cu₉), η₂(AlCu) and θ(Al₂Cu) forme during diffusion welding of copper and aluminum. Fracture occurres along the original welded interface of joint enclosed by the compound η₂.

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The casting characteristics of various Al-Li alloys were investigated. Li losses in Al-3%Si-1%Mg-0.15%Zr containing 1, 2 and 3%Li are about 0.1, 0.2 and 0.4%, respectively when the alloys were melted and held for 3ks at 973K in air. The hydrogen content of molten Al-Li alloys is lowered from 1.00ml/100g to 0.75ml/100g when the Ar degassing time is extended from 300s to 1.8ks at 973-983K. The phenol resin-bonded sand mold coated with MgO, heated and then cooled in vacuum is suitable for casting of Al-Li alloys. The fluidity of Al-2%Cu-1%Mg-0.15%Zr and Al-3% Si-1%Mg-0.15%Zr alloys is not almost changed by the addition of Li up to 3%. The fluid length of these Al-Li alloys is inferior around 85% to that of AC4C (Al-7%Si-0.3%Mg).

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The present work is on the development of casting core of extrusion die for a hollow shape of 6063 aluminum alloy. The static stress distribution of a hemispherical core during extrusion was analyzed by finite element method. The adoption of hemispherical core is found to be effective in the reduction of die weight and in the moderation of peak tensile stress on the core, which in turn improves the life of die, in comparison to a conventional port-hole die. The cooling arrangement for unidirectional solidification of near-net shape cast block was determined through a solidification simulation, which could attain the mechanical properties necessary for cast materials. By machining a hemispherical core die from the near-net shape cast block, the machining time is shortened by 50%, the machining yield increases 2.6 times and the amount of raw material is reduced by 38% in comparison to a hemispherical core die made from a forged ingot. The displacement during extrusion of the shape of the cast core is less than that of a hemispherical core made from a forged ingot.

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Rapidly solidified flakes of Al-8%Mn alloys containing Fe, Cr, Co, Ce, Fe+Ni were produced by using an apparatus combining atomization and water-cooled single copper roll. The flakes were MA processed for 30 h by a high energy ball mill. Consolidation of the flakes and MA powder was done by cold pressing, degassing and hot extrusion. The effect of MA processing on the properties of rapidly solidified Al-Mn base alloys was studied. Hardness, strength and thermal stability of rapidly solidified Al-8%Mn alloy were improved by addition of the third elements, and P/M materials with 4%Co addition showed the highest improvement. The properties were further improved by applying MA, due to fine and uniform dispersion of aluminides, oxide and carbide. MA-P/M materials with 2%Ni+2%Fe addition showed tensile strengh as high as 700MPa at room temperature, and those with 4%Co addition showed the highest tensile strength of about 230MPa at 573K. However, ductility was decreased by MA treatment.

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