Investigation of Ageing Phenomena in CuAlNi Based Shape Memory Alloys
The ageing phenomena and its effect on the thermoelastic martensitic transformation was investigated in three Cu-base SMAs. The transformation temperatures shifted to higher temperatures due to aging in the beta-phase. To increase the alloy’s ductility, a definite amount of Mn (4 wt%) and Fe (2 wt%) were added to the ternary alloy. The thermoelastic martensitic transformation was found in the not-aged samples of the CuAlNiMn and CuAlNiMnFe alloys. This transformation was destroyed due to ageing heat treatments by a fairly unknown exothermic process. The thermoelastic martensitic transformation appeared again in the aged CuAlNiMn and CuAlNiMnFe samples after keeping them on room temperature for a few months. This phenomena was investigated by DSC, SEM, TEM, and XRD.
J. Gyulai and P.J. Szabó
M. Benke et al., "Investigation of Ageing Phenomena in CuAlNi Based Shape Memory Alloys", Materials Science Forum, Vols. 537-538, pp. 129-136, 2007