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Hole-Free Phase Plate Imaging of a Phase Grating
Marek Malac, Misa Hayashida, Ken Harada, Keiko Shimada, Kodai Niitsu, Teddy Rowan, Marco Beleggia
Journal:

/ Volume 24 / Issue S1 / August 2018

Published online by Cambridge University Press:

01 August 2018, pp. 894-895

Print publication:

August 2018
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Transformation entropy change and precursor phenomena in Ni-rich Ti–Ni shape memory alloys
Kodai Niitsu, Yuta Kimura, Ryosuke Kainuma
Journal:

Journal of Materials Research / Volume 32 / Issue 20 / 27 October 2017

Published online by Cambridge University Press:

25 September 2017, pp. 3822-3830

Print publication:

27 October 2017
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Many issues concerning the transformation behaviors in the Ni-rich Ti–Ni system remain unresolved, such as the isothermal nature of the B19′-martensitic and R-phase transformations and the precursor phenomena in the B2-parent phase. To clarify the origins of these behaviors, we investigated the transformation latent heat, specific heat, and superelastic behaviors of several Ni-rich Ti–Ni alloys in terms of the entropy change. An anomalous, very wide hump in the specific heat was detected for the B2-parent phase, which can likely be attributed to the precursor phenomenon in the B2-parent phase. In the critical region where the anomalous hump intersects the B19′-martensitic transformation, some evidences of the R-phase transformation were observed, such as a tweed-like microstructure and a specific heat peak with first-order-transformation characteristics. These findings suggest a strong relationship between the R phase and the precursor state in the B2-parent phase.

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