FeNiCoAlTaB superelastic and shape-memory wires with oligocrystalline grain structure

Abstract

FeNiCoAlTaB shape-memory alloys are desirable alternatives to other smart metallic materials owing to their low base metal and processing costs. These alloys, however, require strong texture via thermomechanical treatments or directional solidification to obtain good functional properties. Here, we demonstrate the fabrication of FeNiCoAlTaB shape-memory wires by a rapid, continuous wire-casting process. These untextured wires exhibit 7% superelastic strains and 1.2 GPa tensile strength after training, and show good cyclability and low stress hysteresis at room temperature. These properties far surpass previous reports in untextured polycrystalline ferrous alloys, an improvement which we attribute to their unique oligocrystalline grain structure.