Cu-Al系2元合金における共析および亜共析組成の恒温変態について

抄録

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 T_c, 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.