Effects of Na and Ti(B) contents, cooling rate, adding condition of Sb, and holding temperature of the melt on Sb modification and mechanical properties were examined. Na more than 10ppm in the alloy interferes modifying eutectic Si and lowers the mechanical properties. Ti(B) 0.05 to 0.10% in the alloy refines the grain size. Sb modification is governed by the degree of eutectic supercooling which depends on the cooling rate in the solidification range. Addition of Sb 0.15% to the Al-7%Si alloy at 740°to 750°C results in modification of eutectic Si crystals, and succeeding addition of Mg 0.3% does in superior strength and ductility. The effect of Sb modification remains after 2nd remelting and holding for 40hrs at 750°±10°C.

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Electrode potential and weight loss of aluminum and anodized aluminum in alcohols were measured. Continuous measuring of the surface electrode potential (VS. Pt) using a high sensivity potentiometer shows that aluminum is uncorroded in alcohols at temperatures below 90°C and the action is moderated with increase of the carbon number in alcohols. Water in alcohols suppresses corrosion. Straight chain alcohols react more vigoulously than the other ones.

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Hexagonal and broken cell morphologies on the solid-liquid interface were examined in dilute Al-Cu alloys unidirectionally growing from seed crystals with growth planes {100}, {110}, {111} and various high index planes. Hexagonal cells are produced on the solid-liquid interfaces with all growth orientations investigated and are transformed to broken cells with decreasing G/RC₀. Morphologies of hexagonal cells on {100} growth interface show the most well-ordered hexagons and permit a wide range of G/RC₀. These hexagonal and broken cells unnecessarily grow parallel to the heat flow direction and deviate toward <100> direction, if the mean interface has high index orientations. The deviation is enhanced with the broken cell interface. Such a result is a sufficient evidence for the fact that these cells essentially have <100> prefered growth orientation similarly as dendrites.

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An anodic dissolution test in NaCl solution, electrochemical polarization measurements and a corrosion test in AlCl₃ solution were carried out. The order of corrosion potential after pit growth is; high purity aluminum< Al-Mg<aluminum<Al-Mn. The order qualititatively agrees with that in AlCl₃ solution. Active dissolution types of electrochemical polarization characteristics are observed in AlCl₃ solution. Corrosion rates estimated from polarization curves coincide with those from an immersion test. Corrosion potentials, E_corr, on pitted materials are explained on the bases of anodic polarization characteristics in AlCl₃ and cathodic polarization characteristics in NaCl solutions. Change of E_corr value with pit growth can be understood considering expansion of local anode area.

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This work on indirect extrusion of aluminum shows that a tendency to excessive grain growth depends on the effective angle of the deformation zone, but not on the dead metal. The fact is contrary to the conventional hypothesis in which the origin of the coarse-grained peripheries in aluminum hot-extrusions is intense local shear at the dead zone interface and that in the peripheral metal adjacent to the container wall. The strain and the strain rate are only minor factors contributing to producing the peripheral coarse-grained zone. A steep gradient of strain rate, i.e. "acceleration of strain" near the die edge appears most likely to be the origin of the peripheral coarse-grained structure in aluminum extrusions.

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Influences of sodium hydroxide and sodium aluminate concentrations, stirring velocity, temperature and particle size of the ores were studied. The leaching reactions gradually proceed with the prolonged leaching time. The leaching rates are accelerated by increasing the sodium hydroxide concentration and the surface area. The apparent activation energies calculated from the Arrhenius plots are 19.6, 17.1, 10.5 and 12.5kcal/mol for gibbsite, boehmite, Seaba ore and Comalco ore respectively. The leaching rates are independent of the stirring velocity and addition of sodium aluminate into the leaching solution. The rate-determing step in the leaching reactions of gibbsite, boehhite and buxite ores is a chemical reaction process rather than mass transport one. The leaching rates for gibbsite and boehmite are expressed as K.A.C_NaOH. exp (-19600/1.987T) and K.A.C_NaOH. exp (-17100/1.987T) respectively, where K is the rate constant, A the surface area of aluminumhydroxide, C_NaOH the sodium hydroxide concentrationand T the absolute temperature.

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