Affiliations: [a] Universidad del País Vasco, Depto.
Electricidad, P.O. Box 644, E-48080 Bilbao, Spain | [b] Institute Laue Langevin, 6 Rue Jules Horowitz,
F-38042-Grenoble Cdx 9, France | [c] Institute of Magnetism, Kyiv 03142, Ukraine | [d] Department of Appl. Physics, Tohoku Gakuin University,
Tagajo 985-8537, Japan
Correspondence:
[*]
Corresponding author (Present address): Universidad del
País Vasco, Dpto. Electricidad, P.O. Box 644, E-48080 Bilbao, Spain.
E-mail: jon@we.lc.ehu.es
Abstract: We present results of an extensive neutron diffraction study of the
martensitic transformation in Shape Memory Alloys of nominal composition
Ni_{55-x}Fe_{19+x}Ga_{26}
(x=0, 1, 2) at. % transforming close to room temperature.
The x=0 sample shows a martensitic transformation temperature
T_{M}≈ 250 K and Curie temperature
T_{C}≈ 289 K. Neutron measurements for this alloy were
performed between 300 K (austenite phase) and 150 K (martensitic phase). At
temperatures T>T_{C} we have found the coexistence of two
phases: an L2_{1} phase with space group Fm3m and cell
parameter a=5.730Å and a γ-fcc with
cubic symmetry and with cell parameter a=3.586Å This second
phase was also detected by magnetic measurements, giving rise to a second Curie
temperature of about 363 K.
