Electrochemical measurements and immersing corrosion test are carried out. MgZn₂ reprecipitates are the besest in all the alloy phases, and slight intergranular attack occured by potentiostatic dissolution at the applied potential-1100 mV vs SCE. Cu addition results in precipitation of noble Al₂Cu and an increase in pitting potential. Grain boundary in the alloys containing Cu 0.7% or more are preferentially attacked, but the phase around grain boundaries remain unattacked in galvanostatic anodic dissolution at 1mA/cm². The fact mearly coresponds with the result of immersion corrosion test in tap water. EDXS analysis shows a Cu depleted zone around grain boundary in the alloys containing a large amount of Cu. Intergranular corrosion of Al-Zn-Mg-Cu alloys arises not from preferential dissolution of grain boundary precipitates but from that of Cu depleted zone. Stress corrosion cracking sensitivity of the alloys hes no distinct relationship with the intergranular attack.

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The relationship between stress corrosion cracking and intergranular corrosion was investigated on 2017 alloy with various aging structures. The alloy aged at 180°C for 5hr shows the highest susceptibilities to SCC, and to intergranular corrosion. This means that a correlationlies between SCC and intergranular corrosion.
The pitting potential is different in grain boundaries and grains each other. Intergranular corrosion is attributed to the difference in pitting potential.
The time to failure is shortened by anodic polarization, but is prlonged by cathodic polarization in potentiostatic SCC tests. SCC of the alloy is caused by active path corrosion. Intergranular corrosion acts as an active path.

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Solidification phenomena of squeeze cast Al-Si alloy AC8A were investigated by measuring and calculating temperture changes of the mold and castings in comparison with gravity casting. As the pressure applied to the molten metal increases, the temperature gradient during solidification increases. The solidification manner changes from mushy type to skin-formation type by applying pressure. The heat transfer coefficient at the casting-mold interface in squeeze casting is four times as large as that in gravity casting, the value being 0.2cal/Ccm²sec and 0.05cal/Ccm²sec respectively. The improvement of the quality of castings by squeeze casting is, at least to some extent, caused by the facts above mentioned.

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The quench sensitivity of Al-Zn-Mg-Cu alloy containing 0.2%Cr, 0.2%Zr and 0.2-0.4%Hf, respectively, was studied by means of hardness and electrical resistivity measurements and electron microscopy. Specimens were cold- or hot-rolled before solution-treatment. It was shown that, only in the alloy containing Zr or Hf, quench sensitivity was affected by working and it became higher with increasing reduction. The influence was moderate in hot-working compared with that in cold-one. The highest quench sensitivity of Cr contained alloy was always observed irrespective of working. The said phenomenon of Zr or Hf contained alloy was understood as follows: The coherency at interfaces, which remained even after working between matrix and Al₃Zr (or Al₃Hf) particles, was inclined to disappear due to recrystallization during solution-treatment, so that the particles acted as heterogeneous nucleation sites for η phase.

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Mechanical properties were evaluated by tensile and Kahn's tear tests for 2024 alloy thermomechanically treated. The highest tensile and proof strength value 60kgf/mm² and 54kgf/mm² respectively, are achieved by FTMT. The FTMT materials aged to the peak strength show significant decreases in elongation and toughness.
Under-aged FTMT materials have higher tensile strength than T6 materials at the same value of elongation. These mechanical properties of FTMT materials are essentially unchanged when warm rolling at 180°C is applied in place of cold rolling at room temperature.

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Inflences of such additives as Sr, Ca and Ba up to 0.1% to the AlCl₃-NaCl-KCl electrolytic bath operating at 280°C and at 0.5 A/cm² on the particle size distribution, alumina contents and recovery efficiency of aluminum powders were studied. Shape of electrodeposited aluminum is modified by the additives. A low alumina content and coarsened size distribution of the deposite are attained by a single addition of optimum quantity of Ca0.005wt% and Ba0.02wt% and remarkably by that of Sr0.02wt%. Cu, Pb, Fe, Mn and Si are not so effective as Sr, Ca and Ba.

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