Properties of Co-Alloyed Ni-Fe-Ga Ferromagnetic Shape Memory Alloys

V. A. Chernenko, IENI, CNR
K. Oikawa, Tohoku University
M. Chmielus, Boise State University
S. Besseghini, IENI, CNR
E. Villa, IENI, CNR
F. Albertini, IMEM, CNR
L. Righi, Parco Area delle Scienze
A. Paoluzi, IMEM, CNR
Peter Mullner, Boise State University
R. Kainuma, Tohoku University
K. Ishida, Tohoku University

Abstract

It is experimentally found that in the Ni₅₄Fe_20-x Co_x Ga₂₆ ferromagnetic shape memory alloys, Co variation from 0 to 9 at.% leads to: (i) almost linear change of martensitic transformation temperatures from −70 °C to 120 °C; (ii) a non-monotonous change of the Curie temperature, and (iii) a linear decrease of saturation magnetization from 60 to 43 Am²/kg. The selected alloys grown as single crystals have been (magneto-) mechanically tested. The superelastic effect has been measured to be about 4%. The magneto-strain shows a training effect which is an evidence of the effect of magnetic-field-induced twin-boundary motion.