Stability of a Ni-rich Ni-Ti-Zr high temperature shape memory alloy upon low temperature aging and thermal cycling
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2016 Elsevier B.V. The thermal stability of Ni50.3Ti29.7Zr20 with aging in austenite at 250C has been studied for three distinctive microstructures obtained after selected thermal treatments: precipitate free and containing two different sizes and densities of H-phase nanoprecipitates. The martensitic transformation is suppressed after 13weeks aging, depending on the initial microstructure, due to a B2 phase instability in the form of short range atomic reordering within the Ti+Zr sublattice, considered to be precursor to the H-phase precipitation. Thermal cycling leads to notable changes in the transformation temperatures, which strongly depends on the starting microstructure.