The Influence of Deep Cryogenic Treatment after Supersaturation of Al 4.7% Cu Alloy on Transformation during Ageing. Studies of Dilatometry, DSC, Hardness and XRD
Studies of dilatometry, DSC, hardness and XRD have shown that a low temperature cryogenic treatment immediately after supersaturation affects changes of structure and properties taking place during ageing after supersaturation. The third peak visible on DSC diagrams for samples conventially treated disappears on DSC diagrams for deep cryogenically treated samples, and the intensity of the two first peaks on DSC diagrams of deep cryogenically treated samples is a few times lower than on diagrams for conventionally treated samples. The dissolution process for precipitation of Al2Cu in conventionally treated samples progresses faster. Hardness of samples aged after a deep cryogenic treatment within the range of 175-220 oC for more than 60 minutes was higher than of those conventionally treated; at higher ageing temperatures (275-350 °C) the differences in hardness were smaller.
Andreas Öchsner and Graeme E. Murch
I. Wierszyłłowski et al., "The Influence of Deep Cryogenic Treatment after Supersaturation of Al 4.7% Cu Alloy on Transformation during Ageing. Studies of Dilatometry, DSC, Hardness and XRD", Defect and Diffusion Forum, Vols. 273-276, pp. 724-730, 2008