This work deals with mechanical properties of the Al-Si-0.15%Sb alloy containing different amounts of Si from 1 to 13% and with effects of Mg and Fe on the mechanical properties of Al-7%Si-Mg alloy. The ultimate and yield strength of Al-Si-0.15%Sb alloy gradually increases with increase in Si content, but the elongation and Charpy impact value rapidly decrease at Si content 6 to 8% or more. The ultimate and yield strength of Al-7%Si-0.2% and Al-7%Si-0.006%Fe alloys exponentially increase with Mg content up to 0.4%. Increase of Mg up to 0.4% rapidly decreases the elongation and impact strength. 0.1 to 0.35%Fe in the Al-7%Si-0.2%Mg alloy provides the maximum ultimate tensile strength, but more of Fe rapidly reduces it. Increase in Fe gradually increases the yield strength, but exponentially reduces the elongation and impact strength.

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Mechanical behaviors in tensile and creep tests at room temperature were investigated for a model material of the superplastic Al-Zn eutectoid alloys. The equation σ= Kε^m. is proved in the alloys which are isotropical and non-work hardenable. The maximum load poit or the initiative poit of tertiary creep bears no relation to the initiation of necking. The increasing poit of ε at which the equation σ = Kε^m becomes unapplicable can be regarded as the real initiation of necking. Where ε is strain rate, σ true stress, and K and m coefficients of strain rate sensitivity.

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The mechanism for stress corrosion in the Al-Mg alloy is investigated. Charged hydrogen has an influence to the susceptibility to stress corrosion and lowers the life. The upper and lower critical concentrations are found. Increase in the susceptibility is saturated beyond the former at the amount of hydrogen increase 0.35 cc/100g and the susceptibility is unchanged below the latter at 0.15 cc/100g. The amount of hydrogen absorbed in the alloy exceeds the latter even in the normal stress corrosion condition. The stress corrosion cracking proceeds through the following stages. i) Electrochemical pitting ii) A strong acid atmosphere constituted near the bottom of the pitts by impediment in fluidity of corrosive mediums leads to a continuous reaction accompanying hydrogen generation iii) A part of generated hydrogen absorbed and concentrated in grain boundaries results in formation of embrittle paths iv) Cracks nucreate when a concentrated stress exceeds a fracture strength of embrittled region, and stop by stress relaxation caused by crack opening or by reaching to an unembrittled region. And v) the stages above mentioned are repeated.

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Fatigue tests on nonisoaxial aluminum bicrystals were carried out under such conditions as the rate of cycles 30.4 Hz and the maximum strain on the surface of specimen 0.16 to 0.19% using a Shenk type bending fatigue machine newly devised. A primary fatigue crack initiates at the crystal boundary affected-regions or at the notch of specimens. In the former cracking initiation, the value of N_ij between primary slip systems in two components crystals is small, and dislocations parallel to the crystal boundary plane in these slip systems or those in either one of component crystal have more screw component than edge one. While in the latter cracking initiation, the value of N_ij is large, and those dislocations have more edge component than screw one. It appears that plastic and elastic strain compatibilities are not a dominant factor causing fatigue cracks to initiate at the crystal boundary affected-regions, but may have a possibility of promoting the initiation of fatigue crack in the crystal boundary affected-resions.

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Alkyl groups in such alcohols as hexyl, octyl, nonyl and dodecyl alcohol were introduced on the surface of anodized aluminum film through a chemical treatment, and contact angles and corrosion resistance were measured to examine a hydrophobic effect. An anodized film prepared in sulfuric acid aqueous solution was dipped in a mixed solution of alcohols and carbon tetrachloride containing phosphorus pentoxide as a dehydrater. The treated film has angles considerably extended to various liquids and higher resistance to alkali corrosion than the untreated one. As the value of carbon number in alcohols increases, the contact angle θ is enlarged. IR spectrophotometry on the absorption of CH in 2870 to 2960 cm^-1, CH₂ and CH₃ in 1470 cm^-1 shows that the effect depends on the substituents.

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The preceding paper described that Sn-rich phases in an Al-4%Cu alloy having a small amount of Sn play a role for precipitation sites for θ' phases resulting in acceleration of aging at high temperatures. The present work concerns the precipitation process of θ" phases (or G. P. (2) zones) in the alloy at aging temperatures from 100° to 175°C. Heterogeneous precipitation of the coherent θ" phases was theoretically expected. Specimens for high resolution transmission microscopy were homogenized at 520°C, quenched and then either aged at the temperature noted above or up-quenched at 200°C for 10 to 60 sec followed by the aging. The θ" phases in the ternary alloy precipitate on the Sn-rich phases (_??_20Å) formed at an early stage of aging. The phases in the binary alloy precipitate on dislocation loops. It is emphasized that the θ" phases precipitate in the ternary alloy in the essentially different process from in the binary alloy. This fact may lead to a peculiar aging behavior at low temperatures.

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