The relationship between the microstructures and tensile properties has been investigated for the vacuum sintered and the vacuum sintered plus HIP'ed Ti–13 mass%V–11 mass%Cr–3 mass%Al alloy, which is the basic material of practically used β–type titanium alloy. They were produced by blending a pure titanium powder, a pure vanadium powder, a pure chromium powder and an Al–42 mass%V alloy powder. The microstructures of the vacuum sintered material and the HIP'ed material consist of equiaxed grain and that of HIP'ed at the temperature near to the β transus becomes finer than the vacuum sintered material. In the materials HIP'ed at the temperatures below the β transus a larger amount of α phase precipitates is observed than in the vacuum sintered materials and the materials HIP'ed at the higher temperatures above the β transus. This tendensy is notable in the low temperature HIP'ed materials after high temperature vacuum sintering. The low temperature HIP'ed materials with many α precipitates show the higher values of the 0.2% proof stress and ultimate tensile strength comparing with the high temperature HIP'ed materials but the ductility is excellent for the high temperature HIP'ed materials. The ductility of the low temperature HIP'ed materials having ununiform α precipitates is lower than the vacuum sintered material. The high strength is obtained but the ductility decreases remarkably by aging the as-HIP materials for the shorter time compering with the ingot material.

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5052 aluminum alloy matrix/titanium composites with about 8, 18 and 47 volume percents of titanium were fabricated by a simple method; compressing alternately multilayered 5052 aluminum alloy foils and pure titanium foils at room temperature. The initial thickness of titanium foils was 10, 25 or 102 μm and that of 5052 aluminum alloy foils was 115 μm. The composites obtained show the multilayered structure of the aluminum alloy and pure titanium phase extended in two dimensions. Many cracks are generated in titanium foils with the initial thickness of 10 μm during compressing and the number of cracks formed decreases with increasing thickness of titanium foils. No crack is detected in titanium foils with thickness of 102μm. Interlaminar shear strength between the aluminum alloy and titanium phases increases with the volume fraction of titanium phase and with the total reduction. The measured values of tensile strength of the composites are nearly in agreement with the values estimated from the rule of mixture on continuous-reinforced composites.

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The effects of Mn addition on toughness of welded Al–Mg–Si alloys have been investigated. In-situ SEM observations of fracture toughness tests have also been used to characterize crack initiation and propagation behavior through the weldment. Recrystallization of HAZ is completely suppressed by adding Mn, while a sample without Mn exhibits recrystallized coarse grain structure. Recrystallization in HAZ can lead to drastic decrease of its fracture toughness comparing with the samples containing Mn. Many microcracks are distributed at grain boundaries within several mm ahead of a crack-tip where crack-tip stresses are relatively weak. Fracture-mechanical analysis reveals that the toughness degradation is attributed to such premature damage evolution before the onset of crack extension. However, the microcracking is not attributed to so-called liquation cracks, but degradation of the grain boundaries due to the formation of film-like Al–Mg intermetallic compounds. The microcracks ahead of the crack-tip aligned at an angle of approximately 60° from an initial notch direction. Tension obliquely applied to the HAZ next to welding pool appears to give rise to such inclination of the microcracks. It is suggested that the toughness degradation can be suppressed by utilizing such anisotropy even if the GB films are formed during welding.

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A SiC_p/7075 aluminum alloy composite has been fabricated by a vortex method followed by squeeze casting, extrusion and rolling. The composites were hot rolled to the total rolling reduction of about 94% at temperatures between 573 K to 773 K and at a rolling strain per pass of 0.10. Superplastic characteristics such as microstructure and apparent activation energy were compared with these of the composites made by other processes in order to clarify the superplastic deformation mechanism. Fine grain size of about 1 μm was attained in the composite rolled at a temperature of 573 K and at the strain per pass of 0.1. In the case of rolling at 573 K, the composite obtained exhibited high strain rate superplasticity with a maximum elongation of about 230% at strain rate of 7 × 10⁻¹ s⁻¹ and at 798 K. Plots between ε^1/n and σ showed linear relation when exponent of n=2 was assumed. Threshold stress obtained from the linear relations were largely dependent on the testing temperature. Apparent activation energy determined from relationship between strain rate and testing temperatures was 244 kJ/mol, which was smaller than that for the powder metallurgical and mechanically alloyed aluminum composites. It seems that there is no substantial difference of high strain rate superplastic mechanism between the composite fabricated by a vortex method and powder metallurgical aluminum alloy composites.

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Tensile strength of 6061–T6 aluminum alloy is presently investigated in the wide ranges of temperature and strain rate. At high strain rates a split-Hopkinson pressure bar method is adapted. Temperature and strain rate effects on the stress strain relations are clarified and can be understood in connection with the thermally activated process concept.

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The purpose of the present work is to clarify the factors that cause the difference between the 99%–foil and the 98%–foil in volume fraction of cube component in high-purity aluminum foils for electrolytic capacitors. The growth behavior of the cube-oriented grains during the final annealing was investigated in detail using SEM–EBSP technique. A remarkable difference was seen in grain size and distribution of the cube and R components between the two foils at the heating point of 300°C during the final annealing. On the basis of these results, the formation process of the residual non-cube grains that are controlled by the difference in the grain size distribution of cube grains after primary recrystallization is discussed. It was thought that the maximum grain diameter is an influential factor in the process, and it depends on the thickness of the foil. Furthermore, it was discussed that the size distribution of cube-grains after primary recrystallization is affected by the factors that exert influence on the driving force of grain boundary movement. These factors are the heating rate in the final annealing, the reduction rate in light-rolling and particularly the size distributions of cube nuclei formed after the intermediate annealing.

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For the present, both electroplating sludge and aluminum dross are treated as waste substances. In this work, metallic nickel recovery from the nickel electroplating sludge was investigated by applying the thermit reaction between NiO in the sluge and Al in the aluminum dross. For industrial application, a coke-bed type blust furnace was used, and the briquettes made from the burned sludge powder and the dross powder were throwed in the furnace. Metallic nickel could be efficiently recovered by the thermit reaction. Continuous utilization of thermit reaction in the blust furnace was ascertained to be possible by the operation controll to keep the constant temperature in the furnace from overheating owing to the exothermic reaction. Environmental safeties for slag and exhaust gas were also ascertained by the elution test and the gas analysis.

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