Ordering transitions in quenched Au7Cu5Al4 alloy and effect of order on martensitic transformation

A metastable phase of DO3 ordering was observed between 171.6 °C and 281.3 °C in quenched Au7Cu5Al4 alloy followed by heating at 2 °C/min. With further increasing of temperature, B2 → A2 order–disorder transition happened above 495.3 °C and finished at 616.5 °C. The evolution of metastable DO3 ordering at 200 °C was also studied. Martensitic transformations of corresponding ordering structures were investigated by DSC. It is found that both the DO3 and B2 ordering suppressed the martensitic transformation start (MS) temperature dramatically, contrary to the L21 ordering which favors martensitic transformation. The effect of order on martensitic transformation in quenched Au7Cu5Al4 alloy was also discussed.