Sen-ichi Yamada1 and Noboru Komatsu1
1Toyota Central Research and Development Laboratories, Inc., Nagoya
In the internal oxidation of Cu-1%Al alloys, the oxidation rate and the effect of the alloying elements on the formation of dispersion particles were studied.
Four elements, Ag, Pd, As and In, were selected as the alloying elements. The former two elements have lower absolute values of free energy of oxide formation than Cu. The latter two have the values higher than Cu but lower than Al. Cu-1%Al alloys containing 0.5 ∼ 1.5% of the alloying elements were investigated by electron microscopy and the X-ray diffraction method. The following results were obtained;
(1) The alloys containing Ag, Pd or As showed almost the same rate of internal oxidation as Cu-1%Al alloy. But the rate of the In-containing alloy was much slower than that of the Cu-1%Al alloy. The internal oxidation did not proceed deeper than 30 μ from the surface with the alloy in excess of 1%In.
(2) In the alloys containing Ag, Pd or As granular α -Al2O3 and γ -Al2O3 of 300 ∼ 600 Å in size were formed by internal oxidation, while In2O3 was formed in the In containing alloy.
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