The degradation of the corrosion resistance was investigated by measurements of polarization curves and potentiostatic or immersed corrosion testes of pure aluminum containing a small amount of Ga as an impurity. The surfaces were observed by SEM and corrosion products were analyzed by EADX of pits of the specimens corroded in the solution of dilute H₂SO₄ and H₂SO₄–NaCl at 303 K. The anodic current density of Al–X mass%Ga alloys (X=0 to 0.2 mass%) in a dilute H₂SO₄ solution under a potentiostatic condition increases with increasing Ga content in the alloys, resulting in the degradation of the uniform corrosion resistance. The pitting potential E_pit of the Al–X mass%Ga alloys in the mixed solution of H₂SO₄–NaCl shifts to a more basic potential with increasing NaCl concentration and Ga content in the alloys. The apparent pitting dissolution rates increase with increasing Ga content in the alloys. The pitting corrosion resistance is thus reduced also. The eflfect of Ga content on the degradation of resistance to the uniform and pitting corrosion is, however, rather small while the Ga content is below 0.02 mass%. The Ga content should be kept less than 0.02 mass% in the pure aluminum.

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This paper proposes a simple method for estimating the flank wear of drill by measuring drilling temperature using infrared ray thermometry in the non-contact way. The chip forms were examined to correlate chip types with rising drilling temperature. The both relationships between the drilling temperature and chip forms, and drilling temperature and flank wear were discussed. The HSS drills were used in this experiment and a series of drilling tests were performed to using a CNC drilling center by changing the cutting parameters on drilling hyper-eutectic Al–Si alloy. The flank wear of drill and drilling forces were measured. The main results are as follows: (1) The chip forms for drilling can be mainly classified in four types correspond to drilling temperature, so that the drilling temperature can be roughly predicted from chip forms. The flank wear rate of drills related mutually drilling temperature, therefore, it is possible that the flank wear of drill was estimated by measuring drilling temperature with a infrared ray thermometer. (2) There is no difficulty for chip rejection from drilling hole when drilling temperature didn't exceed about 600 K. (3) The hardness of work material around the holes drilled are soften when drilling temperature increased above 900 K.

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The surface was scratched with a sapphire pin and the kind of cracks of film and the relation between destruction of film and scratching force were examined. The increase in thickness of anodic film depresses the destruction of the film and hence improves the wear resistance. Only the lateral crack is observed while the film thickness is less than 40 μm, radial, median, and cone cracks are made by the scratch test of thicker films. In the case of bare aluminum or thin anodic film, the sapphire pin digs into aluminum substrate and the deformation force is larger due to the larger deformation volume.

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Microstructure and wear properties of an Al–7.8 mass%V–4 mass%Fe P/M alloy were examined with a transmission electron microscope (TEM) and a wear testing machine. It is confirmed by TEM that icosaphedral quasicrystalline (Q.C.) particles with a size of about 400 nm precipitate in the alloy. The analysis by an energy dispersive x–ray spectrometer indicates that the composition of Q.C. particles is Al–20.3 mass%V–6.7 mass%Fe. The rapidly quenched ribbon with the same composition that of Q.C. particles consists of a nearly single phase of Q.C.. The structure and morphology of Q.C. particles remain unchanged after heat treatment for 200 h at 573 K, indicating that the Q.C. phase is stable even at high temperatures. The wear measurement was made for the Al–7.8 mass%V–4 mass%Fe alloy and commercial aluminum alloy A390–T6. For both alloys the specific wear rate at slid ing velocities from 0.5 to 1.3 m/s is almost constant, i.e., 2.6 × 10⁻⁷ mm²/kg for Al–7.8 mass%V–4 mass%Fe alloy and 2.5 × 10⁻⁷ mm²/kg for A390–T6 aluminum alloy. The specific wear rate of Al–7.8 mass%V–4 mass%Fe alloy remains independent of the sliding velocity up to 2.0 m/s, while that of the A390–T6 aluminum alloy increases rapidly at sliding velocities above 1.3 m/s. These results indicate that the Al–7.8 mass%V–4 mass%Fe alloy with high elevated–temperature strength has also high wear resistance.

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Trace amounts of titanium and zirconium are often added to commercial aluminium alloys. Using the high purity Al–Ti and Al–Zr dilute binary alloys with 5 to 6 different compositions, the contributions per unit concentration of the solutes to resistivity, Δρ, are determined at 77 K and 300 K. The Δρ of solute Ti at 77 K and 300 K, Δρ^Ti₇₇ and Δρ^Ti₃₀₀, are 31.5 and 31.8 nΩm·mass%⁻¹ respectively, showing small deviation from Matthiessen's rule (DMR). The solute Zr gives Δρ^Zr₇₇ and Δρ^Zr₃₀₀ as 19.7 and 18.2 nΩ·mass%⁻¹ respectively, showing a negative DMR. The difference between Δρ^Ti and Δρ^Zr expressed per at% is less than 15% of the absolute values, which is roughly consistent with the Linde's law. Temperature of heat treatments (T_H) vs resistivity diagrams (T_H–ρ diagrams), calculated from present Δρ values and the temperature dependence of equilibrium solid solubilities, show the effect of Ti on the resistivity increase is extremely larger than that of Zr especially when heat treated at higher temperatures.

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The behavior of Li₂CO₃ in molten LiCl electrolyte has been studied to produce Al–Li alloys electrolytically by using Li₂CO₃ as a source of Li. The Li₂CO₃ is a promising raw material of lithium because of its low cost, non-hygroscopic property, high purity, etc. compared with LiCl. An anode compartment, which should prevent the cathode from the infiltration of the anolyte with keeping the electrical contact, was formed by using porous Al₂O₃ crucible. By the electrolysis, lithium deposited at molten aluminum cathode to make an Al–Li alloy and the cathodic potential shifted to more positive potential than that of deposition of pure Li because of lower activity of Li in the alloy. On the other hand, the carbonate ion reacted with graphite anode and the anodic potential decreased by almost 1.2–1.3 V than that of Cl₂ evolution when feeding small pieces of Li₂CO₃ into the anode compartment. Therefore, the potential required to obtain the Al–Li alloy is almost half of the theoretical decomposition potential of LiCl. Current efficiency of cathode was more than 90% which was comparable to the electrolysis using only LiCl electrolyte. Main component of the exhaust from the anode was CO₂ with small amount less than 3% of CO. Carbon consumption was almost the theoretical minimum which was 0.5 mol to one mol Li₂CO₃. These results suggest that the use of Li₂CO₃ as a raw material of lithium is very effective to produce high-quality Al–Li alloy with low cost.

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In this paper, abrasive flow machining (AFM), which is effective for improving the precision on property of the surface and shape of a small hole of a Ti–6Al–4V alloy fabricated by electric discharge machining, is described. AFM is a finishing process used on internal shapes which are difficult to finish by other machining methods. It can perform surface polishing removing a small quantity of material by flowing fluid abrasive medium through or across a small gap of workpiece, under a constant extrusion pressure. The shape of a small hole fabricated by EDM is not straight, i.e., the diameter of the entrance is larger than that of the exit, and the machined surface is not smooth, either. The experimental results show that using AFM polishing as finishing process can significantly improve the quality of the machined surface and of the shape of the small hole of the Ti–6Al–4V alloy. It is also shown that the quantity of removal material and the hole precision are remarkably affected by the concentration of abrasive, extrusion pressure, number of cycles and working time.

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Tensile test was performed in order to investigate the effects of precipitates and solute Mg concentration on the tensile properties and serration of Al–5% and –10% Mg binary alloys aged at temperatures between 373 and 573 K. The obtained results are as follows: (1) The yield stresses of 10% Mg alloys aged at about 453 K increased due to the formation of a rod-like precipitate at the early stage of aging. (2) The elongation to fracture decreased with the precipitation of both particle-like and rod-like precipitates. (3) The strain, stress and maximum stress drop at the serration, were varied in relation to the flow stress affected by the formation of precipitates and the change in solute Mg concentration in the matrix.

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