https://doi.org/10.1140/epjp/i2019-12404-x
Regular Article
Thermally induced martensitic transformation and structural properties in Ni-Ta high-temperature shape memory alloys
Firat University, Department of Physics, 23119, Elazig, Turkey
* e-mail: kyildiz@firat.edu.tr
Received:
28
September
2018
Accepted:
16
November
2018
Published online:
9
January
2019
The morphological, structural and martensitic phase transformation properties of the binary Ni-Ta high-temperature shape memory alloys depending on the composition via SEM-EDX, XRD and DSC observations have been investigated. It was found that the different Ta contents did not change the high-temperature shape memory behaviors of alloy samples with completed martensitic transformation above 220°
C, but had a dramatic effect on the reverse transformation temperatures (
) and transformation hysteresis (
) of alloy samples. As the Ta content of the alloy samples decreased, the 
temperatures shifted to high-temperatures (
°
C, and the values arose to temperatures above 100°
C. However, different Ta contents did not cause considerable changes on the morphological and structural properties of the alloy samples. While a very rare dispersed NiTa2 precipitate phase was observed in the microstructure of the alloy samples with Ta contents above 25 at.%, Ni-rich areas were rarely detected in the microstructure of the alloy sample with Ta content below 25 at.%. In addition, no crack formation was observed in the microstructures of the alloy samples.
© Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature, 2019
