Title :
Influence of thermal treatment on local structure and magnetic properties of Ni-Mn-Ga alloys
Author :
O´Connor, C.J. ; Golub, V.O. ; Vovk, A.Ya. ; Kotov, V.V. ; Yakovenko, P. ; Ullakko, K.
Author_Institution :
AMRI, New Orleans Univ., LA, USA
fDate :
9/1/2002 12:00:00 AM
Abstract :
The influence of the thermal treatment on local structure and magnetic properties of Ni-Mn-Ga alloys has been studied using a nuclear spin echo technique and magnetometry. Nuclear magnetic resonance investigations showed that annealing leads to the formation of stoichiometric Ni2-Mn-Ga. Excessive Mn (Ga) causes faults in the atomic layers interchange. According to X-ray data, this transformation is not accompanied by changes of lattice parameter. However this results in increasing Curie and martensite-austenite transformation temperature. The character of the transition can also vary.
Keywords :
Curie temperature; X-ray diffraction; annealing; ferromagnetic materials; gallium alloys; lattice constants; manganese alloys; martensitic transformations; nickel alloys; reverse martensitic transformations; shape memory effects; spin echo (NMR); stacking faults; stoichiometry; Curie temperature; Ni-Mn-Ga; Ni-Mn-Ga alloys; Ni2-Mn-Ga; X-ray data; annealing; atomic layers interchange; ferromagnetic shape memory alloys; lattice parameter; local structure; magnetic properties; magnetometry; martensite-austenite transformation temperature; nuclear magnetic resonance; nuclear spin echo technique; stacking fault; stoichiometric Ni2-Mn-Ga; thermal treatment; Annealing; Crystalline materials; Crystals; Magnetic materials; Magnetic properties; Magnetic resonance; Nuclear magnetic resonance; Powders; Shape memory alloys; Temperature;
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2002.802472
