日本金属学会誌

J. Japan Inst. Metals, Vol. 24, No. 11 (1960),
pp. 752-755

On the Isothermal Transformation of the Hyper-Eutectoid Compositions in Cu-Al Binary Alloys

Hiroyasu Mitani and Norihiko Nakanishi


Abstract:

In the previous report,the authors tried to obtain the T/T/T-diagrams for two kinds of Cu-Al binary alloys containing 11.44 wt% and 12.18 wt%Al respectively. And it was found that some complex phenomena occurred with the decomposition of the β phase at the temperature below the eutectoid temperature. In consideration of the results of this experiment, the following processes may be deemed reasonable. When Th>Tc,β → α or γ2+E and when Th<Tc, β → β1+α → E+α. Th and Tc stand for the temperature of holding and the critical temperature of β → β1, respectively. It has been shown that the transformation β → β1 preferentially proceeds at the temperature below Tc, and some characteristic structures, the so-called rosettes or granular precipitates and sheaths enveloping α have appeared with the formation of β1. Now, to confirm these phenomena again, the authors have carried out some experiments for obtaining the T/T/T-diagrams for the specimens of 12.49 wt%, near the ideal Cu3Al composition, and of 12.96 wt%Al content. From the present experimental results,it was found that the transformation β → β1 predominantly proceeds at the temperature below Tc causes the alteration of Al concentration, and then the eutectoidal decomposition occurs directly from the β phase of the alloy containing 12.49 wt%Al. Some discussions about the mechanism of the transformation β → β1 in Cu-Al binary alloys are appended.


(Received 1960/4/30)

Keywords:


PDF(Free)PDF (Free)     Table of ContentsTable of Contents

Please do not copy without permission.