Abstract.
The phase transformations associated with Shape Memory Effect (SME) can be one step, B19' (martensite) ↔ B2 (austenite), or two/multiple steps which include the intermediate R phase, depending on the thermal and thermomechanical history of the alloy. The transformation temperatures are generally observed above room temperature in Ti-rich Ni-Ti alloys, while those observed in Ni-rich alloys occur below room temperature. The goal of the present work is to investigate the phase transformations evolution in Ti-Rich Ni-Ti SMA (Ni-51 at % Ti) when subjected to two distinct thermal treatments (500°C for 30 minutes in air and 800°C for 300 minutes in vacuum) and subsequently multiple steps of marforming thermomechanical treatments intercalated with thermal treatments (500°C for 30 minutes in air) and subsequent four distinct final thermal treatments (400, 450, 500 or 600°C for 30 minutes in air). Further, the stability of phase transformations in the initial ten thermal cycles of these thermomechanically treated samples is also studied. Differential Scanning Calorimetry (DSC) and X-Ray Diffraction (XRD) were used to identify the transformation temperatures and the phases that are present after the thermomechanical treatments.
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Paula, A., Mahesh, K. & Braz Fernandes, F. Evolution of phase transformations after multiple steps of marforming in Ti-rich Ni-Ti SMA. Eur. Phys. J. Spec. Top. 158, 45–51 (2008). https://doi.org/10.1140/epjst/e2008-00652-8
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DOI: https://doi.org/10.1140/epjst/e2008-00652-8