Promising ferromagnetic Ni-Co-Al shape memory alloy system

A system of ferromagnetic beta phase Ni-Co-Al alloys with an ordered B2 structure that exhibits the shape memory effect has been developed. The alloys of this system within the composition range Ni (30-45 at. %) Co-(27-32 at. %) Al, undergo a paramagnetic/ferromagnetic transition as well as a thermoelastic martensitic transformation from the beta to the beta (')(L1(0)) phase. The Curie and the martensitic start temperatures in the beta phase can be controlled independently to fall within the range of 120-420 K. The specimens from some of the alloys undergoing martensitic transformation from ferromagnetic beta phase to ferromagnetic beta' phase are accompanied by the shape memory effect. These ferromagnetic shape memory alloys hold great promise as new smart materials. (C) 2001 American Institute of Physics.