Shape memory effect due to magnetic field-induced thermoelastic martensitic transformation in polycrystalline Ni-Mn-Fe-Ga alloy

In Heusler-type alloy Ni2+x-yMn1-xFeyGa, partial substitution of Mn for Ni causes the temperatures of structural (martensitic) TM and magnetic TC (Curie point) phase transitions to converge. Close to the crossover of TM and TC, we have observed the strong strains (Deltal/l approximate to 2-4%) induced by the external magnetic field. This effect could be classed with colossal magnetostriction. The system exhibits the magnetic field-controlled one-way shape memory effect at fixed temperature as a result of the magnetic field-induced martensite to austenite structural phase transition. (C) 2001 Elsevier Science B.V All rights reserved.