On the corrosion of non-stoichiometric martensitic Ni-Mn-Ga alloys

Abstract
During the last decade, NiMnGa alloys have drawn an increasing interest due to their shape memory properties, superelasticity and, lately, the magnetic field induced straining effect. Extensive studies have also been devoted to the martensitic transformations, the crystal structures of the martensites and the austenitic parent phases. It has been found that the martensite transformations in nonstoichiometric NiMnGa alloys are highly sensitive to the alloy composition. The properties of these alloys with different compositions have been studied with regard to mechanical, and actuation behaviour. However, the corrosion of these alloys bas little studied. In the present work, the corrosion behaviour of three non-stoichiometric NiMnGa alloys having different compositions and martensitic structure are studied. Particular emphasis is given to the correlation between the corrosion resistance and the martensitic crystal structures of the alloys.