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Burst-like reverse martensitic transformation during heating, cooling and under isothermal conditions in stabilized Ni-Ti-Nb

C. Picornell, J. Pons Morro, A. Paulsen, J. Frenzel, V. Kaminskii, K. Sapozhnikov, J. van Humbeeck, S. Kustov

Scripta Materialia, 180, 23-28, (2020)

DOI: 10.1016/j.scriptamat.2020.01.018

To reveal mechanisms of martensite stabilization by prestrain in shape memory alloys, details of reverse martensitic transformation (MT) in prestrained Ni₄₅Ti₄₆Nb₉ alloy were studied using calorimetry, dilatometry and resistivity. The first reverse MT is burst-like and is shifted to higher temperatures by ~120 K as compared to the nominal MT. During thermal cycling approaching the first reverse MT, stabilized martensite shows “forbidden” behaviours like burst-like reverse MT not during heating, but during cooling and under isothermal conditions. These unusual effects are attributed to non-thermoelastic nature of the first reverse MT in stabilized martensite under high chemical driving force.

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