日本金属学会誌

J. Japan Inst. Metals, Vol. 24, No. 11 (1960),
pp. 748-751

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

Hiroyasu Mitani and Norihiko Nakanishi


Abstract:

Wassermann, Obinata and Kurdjumow reported that the β' martensite is produced from β through β1,i.e. ordered β, on rapid cooling in Cu-Al binary alloys. As it is confirmed that the formation of β1 is not arrested even by water-quenching, it is interesting to find out some microscopic figures about β1 transformed from β, and as it may be supposed that the isothermal transformation of β is affected by the transformation β → β1, the authors have tried to determine the T/T/T-diagram for two kinds of specimens, namely of 11.44 wt% and 12.18 wt%Al contents. As the results of the present experiments, it was found that the process of the formation of β1 had an important part in the T/T/T-diagrams, and the eutectoidal precipitation appeared directly from β1 containing about 12.4 wt%Al at the temperature below Tc, i.e. the critical temperature for the transformation β → β1. It was also observed microscopically that some rosette or granular precipitates and the sheath enveloping α were accompanied by the formation of β1. The probable nature of the decomposition processes of β and β1 has been discussed.


(Received 1960/5/10)

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