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Characterization of martensitic transformation in some Ni-Fe-Co-Ga ferromagnetic shape memory alloys

F. TOLEA1,* , M. SOFRONIE1, C. GHICA1, M. VALEANU1

Affiliation

  1. National Institute of Materials Physics, 077125 Bucharest, Romania

Abstract

The martensitic transformation characteristics in two series of cobalt substituted Ni-Fe-Ga Ferromagnetic Shape Memory alloys have been studied by differential scanning calorimetry, X-ray diffraction, electrical resistivity and thermomagnetic measurements. Co substitution for Fe or Ni promotes an increase of the Curie temperatures but the changes of the martensitic transformation temperatures are in agreement with the valence electron concentration and unit cell volume variations. A large hysteresis observed between cooling and heating curves as feature of a first order phase transition was evidenced by r(T) and thermomagnetic measurements..

Keywords

Ferromagnetic shape memory alloys, Martensitic transformation,Magnetic properties.

Citation

F. TOLEA, M. SOFRONIE, C. GHICA, M. VALEANU, Characterization of martensitic transformation in some Ni-Fe-Co-Ga ferromagnetic shape memory alloys, Optoelectronics and Advanced Materials - Rapid Communications, 5, 5, May 2011, pp.562-566 (2011).

Submitted at: April 20, 2011

Accepted at: May 31, 2011