Al-20%Si alloy castings unmodified and modified with a P-containing flux and metallic Na having primary Si crystals 300 to 400μm and 20 to 30μm in diameter respectively were prepared. A thermal shock cycle, heating at 500°C for 20mn and quenching into ice water was repeated up to 400 times. The modified alloy having refined Si crystals is free from surface cracking after subjected to thermal shock of 400 cycles. The Na modified alloy in which coarse spheroidal Si crystals are segregated deforms ununiformly. All the specimens deform by thermal shock accompanying by internal cracking. The alloy modified with a P-containing flux has the maximum resist-ance to thermal shock.

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Stress corrosion cracking in welds of cold rolled Al-Zn-Mg alloy was studied by means of measurements of mechanical properties and electron microscopy. Fracture of the welded specimens in tensile testing occurs at the area 6 to 7 mm apart from fusion boundaries. SCC fracture of them, on the other hand, occurs at the HAZ about 1 mm far from the fusion boundaries independently of applied stresses, where η precipitates are formed along subgrain boundaries or grain boundaries. Preferential dissolution of these precipitates is associated strongly with initiation and propagation of SCC.

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As a part of a work on the recrystallization texture, the phase of precipitates forming parallel to the recrystal-lization process in Al-0.027Fe and Al-0.034Fe-0.04Si alloys cold rolled and annealed at 280° and 400°C was electron microscopically examined. At 280°C only a metastable phase Al₆Fe precipitates in the binary alloy, and mainly a ternary phase α-AlFeSi forms metastably in the ternary alloy being accompanied by a small amount of Al₆Fe. At 400°C two phases Al₆Fe and Al₃Fe precipitate in the binary alloy, and three phases α-AlFeSi, Al₃Fe and Al₆Fe precipitate in the ternary alloy in almost equal amounts. These facts qualitatively agree with the change by precipitation in concentrations of Fe and Si in solid solution determined by measuringt he electrical resistivity and thermo-power. The phases of precipitates in both alloys have not been observed to be transformed by sweeping of the recrystallization front.

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The earing of cups drawn from circular blanks of FCC polycrystalline metals was calculated crystallograph-ically using their measured texture data represented as a three-dimensional crystallite orientation distribution function. In the analysis the polycrystalline sheet is simplified to an aggregation of single crystals with various orientations of which volume fraction is represented as an orientation distribution function. The circumferencial distribution of a radial strain, which corresponds to the cup profile is calculated. The work-hardening rule of a crystal is expressed by an equation, τ/σ = kγⁿ + μ0 (τ: shear stress, γ: shear strain, σ: radial tensile stress in a flange). The effect of values of unknown constants in the equation upon a calculated result was examined. By comparing the results with experimental ears formed on cups for twelve kinds of aluminum sheets, it is found that the number, positions and heights of ears are predicted not only qualitatively but also quantitatively by the calculation when the values of μ₀ and n are 00.1 and 1.0 respectively, while k is eliminated in the calculation.

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Four electrodes method for measuring the electrical conductivity σ of Na₃AlF₆-Al₂O₃-AlF₆ melts of aluminum electrolytes was improved, in which any cell constants are unessential. This method usually brings the conductivity data more reliable than those obtained by conventional methods. Iso-electrical conductivity lines of the Na₃AlF₆-Al₂O₃-AlF₃ melts were plotted using the data of this method. Dependency of σ on the composition of the melts is discussed in terms of the distribution of ion species (AlF₄^-, AlOF₂^-and AlO₂^-) in this system. A plot of σ for the charge carrier concentration (Na⁺+free F^-) has a linear relationship.

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