Ductility enhancement and superelasticity in Fe-Ni-Co-Al-Ti-B polycrystalline alloy

The microstructure, martensitic transformation and superelasticity were examined in Fe-30Ni-15Co-10Al-2.5Ti-0.05B polycrystalline alloy sheets. Thermoelastic transformation was obtained in an aged specimen at 550 °C with the γ (FCC) + γ′ (L12) structure. Moreover, it was found that a {0 1 2}〈1 0 0〉 recrystallization texture was formed and that the high fraction of low energy boundaries was increased in a 98.5% cold-rolled specimen. Suppression of brittle precipitation during aging was directly observed at those boundaries, resulting in improvement of ductility, and superelastic strain of over 4% was obtained in the polycrystalline alloy in a tensile test at room temperature.