1Mechanical Engineering, Department of Technology, Kanagawa University, Yokohama
When Al-bronze is slowly cooled, it shows a brittleness called ``self-annealing phenomenon of Al-bronze''.
This phenomenon is caused by γ2 produced at β → α + γ2 transformation. Therefore the depressing of the self-annealing phenomenon poses an important problem from the engineering point of view, and it was made clear that additions of Fe and Mn are effective on the depressing of β → α + γ2 transformation.
The present study was intended to investigate the depressing effects of additions of Be and both Be and Fe on the β → α + γ2 transformation of Cu-Al alloy. For this purpose, the T.T.T. diagrams of these Cu-Al alloys were made out through examinations of microstructures. The results obtained are as follows: (1) The nose of Cu-Al-0.63Be alloy was about 462°C, 6.7 × 103 sec and the nose of Cu-Al-0.66Be-3.65Fe alloy was about 525°C, 1.2 × 103 sec. (2) Additional effects of Be and Fe on the depressing of β → α + γ2 transformation was not recognized. However, the isothermal transformation speed of Cu-Al-0.66Be-3.65Fe alloy was slightly slower than Cu-Al-3Mn alloy, and the addition of Be was effective for the depressing of β → α + γ2 + κ transformation of Cu-Al-Fe alloy.
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