Reversible and irreversible martensitic transformations in Fe-Pd and Fe-Pd-Co alloys
Universidad Pública de Navarra (UPNA), Campus Arrosadia, 31006 Pamplona, Spain
2 Institute of Magnetism, NAS of Ukraine, 36-B Vernadsky Str., Kiev, 03142, Ukraine
3 Institut Laue Langevin (ILL), 6 rue Jules Horowitz, Grenoble, France
4 Instituto de Ciencias de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Zaragoza, 50009, Spain
Ferromagnetic Fe-Pd shape memory alloys (SMA) undergo a martensitic phase transformation during cooling from a parent FCC phase to a tetragonal FCT martensite. This transformation is thermoelastic and reversible giving rise to the shape memory effect. On further cooling an irreversible FCT to BCT transformation occurs that makes impossible the memory effect. Nevertheless, the transformation from reversible to irreversible phase has been not complete since a volume fraction of reversible phase in the alloy is retained even after cooling below the temperature of appearance of the irreversible phase. The addition of Co lowers the temperature of the reversible and irreversible phase transformations but also reduces the amount of transformed irreversible martensite after cooling to 10 K.
© EDP Sciences, Springer-Verlag, 2008