The machinability of 99.9% magnesium was studied and was compared with those of 99.9% cadmium, 99.5% zinc and 99.5% titanium. Cutting tests were performed under the Same condition for all the samples and had the following characteristics: cutting Speed of 65-400m/min, feed of 0.04-0.32mm/rev and cutting depth of 1 and 3mm. The following results were obtained:
(1) Except titanium, cutting force was hardly affected by cutting speed. The order of the samples with respect to cutting force was shown as
Ti>Cd_??_Zn>Mg.
(2) Chip shapes of zinc and cadmium changed gradually from a flow type to a sheared type as feed increased. However, titanium always showed a flow type of chips.
(3) Cutting ratios of the samples were in the following order:
Mg>Cd>Zn_??_Ti.
(4) Cutting temperatures depended on the samples and were expressed in the following order:
Ti>Cd_??_Zn>Mg.
(5) Sensitivity of cutting temperature with respect to changes of cutting speed and feed was the largest for magnesium and the lowest for titanium.

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Al-Mn-Cr alloys were anodized in a sulfuric acid solution and color of anodized films was measured quantitatively. Dependence of the color on alloy compositions and heat treatment was studied and a coloring mechanism was discussed in terms of quantum chemistry. Following results were obtained:
(1) When super saturated solid solutions were anodized, films on high manganese alloys showed light pink color while films on high chromium alloys developed yellow color. When contents of manganese and chromium were intermediate, light pink and yellow hues overlapped and the film color turned to be brown because the stimulus value, Y, lowered.
(2) When alloys had been precipitation annealed prior to anodizing, high chromium alloys developed slight coloring. However, the color was grey because of the extremely low stimulus value.
(3) Coloring by manganese and chromium was due to Mn³⁺ and Cr⁶⁺, respectively. Formation of films with slightly greenish color on annealed alloys was possibly due to Cr³⁺ contribution.
(4) Dispersed precipitates in films resulted in blackening by scattering. Scattering by smaller precipitates produced bluish color.
(5) It appeared that the coloring mechanism active in the present study was similar to that of colored glass, laser materials or certain jewels.

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Effect of hot rolling temperature on cup earing and limited drawing ratios of commercially pure aluminum, 1100, was studied mainly from a view point of textures. The results obtained are as follows:
(1) Cup earing depended strongly on hot rolling temperatures; the lower the hot rolling temperature, the higher earing of 45° direction was produced. Textures also depended remarkably on the rolling temperature. Hot rolling at a low temperature favored formation of (224) planes parallel to a sheet plane while a high tempeature rolling produced more population of (200) planes. Changes of cup earing with hot rolling temperaturewere explained from the relative population of (224) and (200) planes.
(2) The limited drawing ratio was also markedly affected by hot rolling temperatures. The specimens, hot rolled at 500°C, showed the maximum drawing ratio. There was a close relation between the limited drawing ratio and the (100) [001] component of the texture. This component decreased with decreasing hot rolling temperature.

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Machinability of wrought aluminum (1100-0) in drilling was studied together with overshooting of cutting force, increase of chip thickness and change of chip shape. Samples of six different thickness (10, 15, 20, 25, 30, 35 and 50mm) were tested by four kinds of tools (4, 6, 8 and 10mm in diameter). The results obtained are as follows:
(1) Torque and thrust were proportinal to drilling depth.
(2) Cutting force increased with feed and cutting speed. Difference between the highest and the lowest cutting force was large for the high feed case and for thick samples.
(3) The drilling limit per pass increased as the drill diameter, the feed speed and the cutting speed increased.
(4) Small shear angles were considered to be produced by a certain mechanism of friction between chips
and tool faces.

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The pitting corrosion of aluminum was investigated by autoradiography with ³²P, ³⁵S, ⁵⁵Fe and ⁵⁵Fe-⁵⁹Fe mixture.
In the first experiment, commercially pure aluminum plate specimens were immersed in approximately neutral solutions containing 5ppm of phosphate labelled with ³²P and 5ppm of chloride, and in those containing 50ppm of sulfate labelled with ³⁵S and 5ppm of chloride. The test solutions had been chlorinated to a free chlorine content of 2-3ppm to induce pitting. After corrosion tests, thin collodion films were coated on the Specimens and autoradiographs were made by means of a contact film method. The distribution of blackening spots of the autoradiographs coincided accurately with that of pits formed on the specimens. Degrees of blackenings increased with pit growth. From these, it can be considered that phosphate and sulfate ions are concentrated radidly into the inside of the pits at the initiation stage of pitting and are adsorbed or precipitated with corrosion products such as aluminum hydroxide around the pits as the pits grow.
In the second experiment, radioactive iron was introduced into high purity aluminum, and then Al-Fe and Al-Fe-Si alloy plate specimens, labelled with ⁵⁵Fe or ⁵⁵Fe-⁵⁹Fe mixture were prepared. The same preparation procedure as that in the first experiment was applied in this experiment. In addition, the newly developed Auger electronmicroautoradiography was used together with the stripping film method. Relatively large pits on the surface of the Al-0.4%Fe-0.1%Si alloy specimens and blackening images of autoradiographs coincided accurately. Precipitation of iron always occurred around each pit and progressed with the lapse of corrosion time.
Furthermore, the results of the identical experiments, carried out for Al-0.045%Fe, Al-0.08%Fe and Al-0.08%Fe-0.02%Si alloy specimens, showed that many tiny and rather large blackening spots of microautoradiographs, observed with a high magnification microscope, were located in the vicinity and the center of micropits. From these, it can be considered that micropits are formed by the local penetrative attack which takes place at the areas neighbouring intermetallic compounds such as FeAl₃ and FeSi₂Al₄, and that iron ions from these compounds in the central parts of micropits are reduced at local cathodic parts around micropits and precipitate there.

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