Dependence of internal friction on temperature was measured by means of low frequency damped vibration for Al-0.8wt% Mg₂Si, Al-0.62wt% Mg₂Si-0.18wt% Si, and Al-0.54 wt% Mg₂Si-0.26wt% Mg alloys aged at 150, 200, and 230°C.
The principal results obtained by experiments were as follows:
(1) The specimens aged had a peak of internal friction at a temperature of 90140°C. The peak would be due to the inner part of the precipitate body.
(2) The activation energy of the peak for a specimen aged at 150°C was 27, 00037, 000 cal/mol, which was nearly idential with that due to diffusion of Mg and Si in Al. When a specimen had been aged at higher temperature, its activation energy of the peak was increased with the rise of ageing temperature. The value of the energy of a specimen aged at 230°C was 42, 00058, 000 cal/mol, which was nearly identical with the atomic bond energy.

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Tensile stress was applied at a constant temperature to an alloy called Magnox (composed of Al 0.79, Be 0.006, Fe 0.0079wt%, and Mg balance). Number of voids and length of grain boundary migration produced by creep were measured.
The principal results obtained by experiments were as follows:
(1) Except for high velocities of creeping such as about 10% elongation/hr., number of voids was the maximum at 300°C for creeping velocity of lower than about 4% elongation/hr.
(2) Though with a few exceptions, the length of grain boundary migration was generally large at the temperature and creeping velocity for a large number of voids. (In most cases, the maximum length corresponded with the maximum number of voids).

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The normal drill grinder with a stepped ground point drill having a chisel edge angle of 90° can drill smaller dimensions of oversize of holes than with the conventional chisel point drill.
However, the optimum condition of drilling aluminum and its alloys by using the drill of the former type is still unknown. This paper discusses the effects of drilling conditions and the shapes of drill points on the dimensions of oversize of holes for materials of 5 kinds of F-metals; 1S, 2S, 17S, 52S, and 61S.
The principal results obtained were as follows.
(1) In dry drilling (with no cutting fluids), the dimensions of the oversize were arranged in ascending order of 17S<52S<61S<aluminum.
(2) In drilling of aluminum, the point angle was obliged to be smaller for decreasing the dimensions of oversize. In drilling of aluminum and its alloys, the pointed chisel drill was effective in decreasing the dimensions of oversize.
(3) In dry drilling of aluminum, the dimensions of oversize were decreased with the increase of feed, but were little affected by cutting speed except for the case of 1S.
(4) The effects of cutting fluids on dimensions of oversize were sometimes different between drilling of aluminum and its alloys. However, emulsions were effective in drilling of the both materials.

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The effects of Si, Fe and Sn on recrystallization of Al-Zr alloys were studied and the following results were obtained.
(1) The recrystallization temperature of Al-Zr alloys was higher with smaller degrees of cold reduction. In addition, pre-heat treatment at 350°C for Al-Zr alloy containing only 0.03% of Si was needed for a longer period than that containing less than 0.02% of Si in order to raise the recrystallization temperature.
(2) The recrystallization temperature of Al-Zr alloys was not lowered by the addition of Fe as far as a small sized permanent mold was used as in the present experiments for casting.
(3) The recrystallization temperature of Al-Zr alloy containing single Si was not so much raised by pre-heat treatment. However, that of the alloy containing both of Si and Fe was distinctly raised.
(4) The period of pre-heat treatment for retarding the recrystallization of Al-Zr alloys was much reduced by the addition of Sn.

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Effects of solution treatment and addition of a small amount of Be on the impact strength and structure of Al-Si alloys containing Fe were examined by means of impact tests.
The results obtained were summarized as follows.
(1) The impact strength of Al-11% Si alloys was linearly decreased with increasing Fe content in the range beyond 0.13% Fe. After solution treatment at 500°C, the strength was markedly improved when Fe content was smaller, and the effect diappeared at about 1.5% of the content.
(2) The impact strength of Al-11% Si alloys tended to be decreased with the addition of Be, both for as cast and heat treated (at 500%C) alloys.
After Al-13% Si alloys containing Fe, to which Be had been added, was heat treated, the strength was markedly varied according to Fe content. It was kept nearly constant up to 1.02 or 1.32% of Fe by the addition of 0.2 or 0.5% Be, respectively.
(3) Acicular crystallites were observed in Al-Si alloys, which had lower impact strength with decreasing Fe content. However, the shape of crystallites was converted into roundish patterns of Chinese script character type.

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