Effects of Au addition (0.0040.25wt%) on age-hardening of Al-1.4wt%Mg₂Si pseudo-binary alloy were investigated by measurements of hardness, tensile tests, and electron microscopy.
It was found that the effects of Au on age-hardening of Al-Mg-Si alloys were not so remarkable as those on age-hardening of Al-Zn-Mg alloys, but the maximum strength of Al-1.4wt%Mg₂Si pseudo-blnary alloy attainable by the age-hardening was increased with the increase of Au content up to 0.084wt%, but was decreased with further increase of Au content.
The most remarkable effect of Au addition to Al-Mg-Si alloys was to improve their ductility (elongation) in age-hardened state. The above effect would be attributed to the inhibition of grain boundary precipitation due to the stabilization of the grain boundary by the addition of Au.

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Effects of Au addition (0.0040.25wt%) on two-steppcd ageing of Al-1.4wt%Mg₂Si pseudo-binary alloy were investigated by measurements of hardness, tensile tests, and electron microscopy.
It was reconfirmed that the effect of two-stepped ageing on deterioration in strength of this alloy was due to the coarsening of acicular G. P. zones. The effects of pre-ageing time on the maximum hardness attainable by the two-stepped ageing were investigated in detail and the results were explained with respect to the change in number of G. P. zones formed before and during the final ageing.
It was found that the strength after final ageing at 160°C was improved by the addition of Au, when the preheating had been made at 0°C. The above effect would be attributed to the retardation of the reaction during pre-ageing by the addition of Au.

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The macro-structural flow during deformation of metals was observed in the extrusions of commercially pure aluminum and 6063 alloy at 500°C under farious extrusion conditions. The deformation behavior concerning the extrusion pressure and the macro-structure obtained by experiments was discussed with respect to the effects of ram speed, die angle, and reduction in diameter.
The following results were obtained:
(1) As for a given extrusion ratio (R) an approximate linear relationship was empirically obtained between extrusion pressure (P) and logarithm of (R). As for a given extrusion velocity (V), there also existed an approximate relationship between logarithm of (P) and logarithm of (V). Each factor expressing the ratio between the values in these relationships depended upon extrusion conditions such as extrusion ratio and extrusion speed. When extrusion pressures were measured for three die angles, the value of (P) was smaller with the increase of die angle (α).
(2) The flow of the macro-structure of cast billet during the extrusion process could be divided into the following zones; dead metal, inner shearing, entry to the die, neck of the die, extruded product, etc. It was found that the extrusion characteristics of cast billets could be explained with respect to the grain refining behavior of structures in these zones.
(3) The microscopic examination of the structure and etching figures showed that the feathery grains having a twin plane of (111) were converted into granular grains having a plane of (110) during hot dynamic extrusion at 500°C. However, the mechanism of the rotation of these deformed crystals remained still unsolved.

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This paper describes one of a series of studies on the deformation process in hot extrusion. The previous paper described that the extrudability could be explained with respect to the deformation resistance and the macrostructural flow. This paper describes that the grid-mark method was applied to the extrusion of commercially pure aluminum and 6063 alloy billets at 500°C, and the experimentally obtained deformation characteristics based on flow line were examined in terms of velocity components. Extrusion was carried out at a speed of 7mm/sec. through three die semi-angles of 45, 60, and 90° and with a extrusion ratio of 9: 1; and billet structures were converted into two different kinds of feathery and granular crystals.
(1) Comparison of flow patterns between the two billet structures under the same extrusion conditions showed little difference in deformation patterns of inner shearing zone, and the deformation zone of feathery crystals extended toward the front of billet further than that of granular crystals. The high velocity distribution observed in the feathery crystal billet seemed to be attributed to the fact that the feathery crystals, having preferential orientation, showed high workability in the direction of crystal growth as described in the previous paper.
(2)When the velocity components were measured for three die angles in hot extrusions, the axial velocity was larger with the increase of die angle. Whereas, the extrusion pressure was lower with the increase of the angle on the contrary to the fact in the previous paper. These facts resulted from the geometrically constrained plastic flow, and it was found that the friction behavior in hot extrusion through 90° die was smaller than that in cold extrusion.

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Studies were made of the composition and structure of boehmite films formed on aluminum sheets in boiling aqueous solutions by electron microscopy, electron diffractiometry, and X-ray diffractiometry; and also made of the effects of kind and concentration of additives on the film.
The following results were obtained:
(1) The results of tests of sheet metals showed that the boehmite film formed on an aluminum sheet consisted of a continuous thin film tightly adhering to the aluminum surface and numerous fine needle crystals, independent of the presence and kind of additives.
(2) Both of the continous thin film and fine needle crystals were composed of boehmite, and the latter were preferentially oriented in (001) planes parallel to the surface.
(3) The results of tests of aluminum powder showed that only boehmite was formed in water after boiled for 15min., and bayerite was also formed together with boehmits after boiled for 1hr. or more. The addition of triethanolamine to deionized water accellrated the growth of boehmite but inhibited the growth of bayerite. Whereas, the addition of ammonia accelerated the growths of both boehmite and bayerite.
(4) The results of X-ray diffractiometry showed that the boehmite formed on aluminum powder was not a standard boehmite, but was judged to be a quasi-boehmite having an excessive water content.

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Studies were made of the effects of aluminum purity and individual impurity elements contained in it upon the formation and corrosion resistance of boehmite films formed on aluminum in boiling aqueous soulutions.
The following results were obtained:
(1) The thickness and corrosion resistance of the boehmite film formed on aluminum depended on the purity of aluminum. The film formed in 0.5% triethanolamine solution after boiled for 1hr. had larger thickness and higher corrosion resistance with the increase in aluminum purity.
(2) The electron microscopic examination and electron diffraction showed that the micro-structure of the film was independent of aluminum purity.
(3) As for impurity elements contained in aluminum, Fe and Cu increased the film thickness at the initial stage of boehmite formation, but decreased it with the lapse of time. These elements served to decrease the corrosion resistance of boehmite film, the effect of which was particularly more remarkable in Fe.
(4) Among impurity elements, Zn increased the thickness of boehmite film, but sharply decreased its corrosion resistance. Whereas, Si and Ti decreased the thickness of boehmite film, but had little effects on its corrosion resistance, except for cases of their high contents.

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