| 1. |
Golasiński K.♦, Maj M., Musiał S., Tasaki W.♦, Kim H.♦, Significant Temperature Change and Inhomogeneous Tensile Deformation of Superelastic Ti–26Nb, Ti–25Nb–0.3O and Ti–25Nb–0.3N Shape Memory Alloys,
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, ISSN: 1073-5623, DOI: 10.1007/s11661-025-08036-4, pp.1-13, 2025 Abstract:
In this work, thermomechanical behavior of the superelastic Ti–26Nb, Ti–25Nb–0.3O and Ti–25Nb–0.3N (at. pct) shape memory alloys (SMAs) under load-unload tension was investigated using coupled techniques of infrared thermography and digital image correlation. Local and average characteristics were analyzed in the context of particular deformation stages. In the case of all the SMAs, during loading, first the temperature decreases due to the thermoelastic effect, which can serve to estimate true elastic strain. During further loading, the temperature significantly increases due to the forward stress-induced phase transformation, whereas during unloading, the temperature significantly decreases due to the reverse phase transformation. The average values of the temperature change generated due to the elastocaloric heating and cooling were 15.95 K, 14.94 K, 16.05 K and 17.79 K, 14.44 K, 19.83 K in the case of the Ti–26Nb, Ti–25Nb–0.3O and Ti–25Nb–0.3N SMAs, respectively. The kinematic fields demonstrated that the deformation during loading and unloading is inhomogeneous. It starts with the appearance of thin parallel bands perpendicular to the loading axis. These bands create larger areas with higher strain upon further loading and gradually reappear upon unloading. The results advance the comprehension of the thermal and kinematic aspects of tensile deformation of superelastic Ti-Nb-based SMAs Affiliations:
| Golasiński K. | - | other affiliation | | Maj M. | - | IPPT PAN | | Musiał S. | - | IPPT PAN | | Tasaki W. | - | other affiliation | | Kim H. | - | other affiliation |
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| 2. |
Golasiński K.♦, Brodecki A., Ranachowski Z., Tasaki W.♦, Pieczyska E., Kim H.♦, Monitoring of Ti-25Nb and Ti-25Nb-1O shape memory alloys in the initial stage of tensile deformation by combined techniques of acoustic emission and digital image correlation,
ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING, ISSN: 1644-9665, DOI: 10.1007/s43452-025-01387-0, Vol.26, No.10, pp.1-13, 2025Abstract:
This work concerns an experimental investigation of the Ti–25Nb and Ti–25Nb–1O (at%) SMAs in the initial stage of tensile deformation using acoustic emission (AE) and digital image correlation (DIC). The stress-strain responses of the considered SMAs are different. The Ti–25Nb SMA exhibits shape memory effect due to the stress–induced martensitic transformation from the cubic β phase to the orthorombic α″ phase. In the case of the Ti–25Nb–1O SMA, the addition of 1 at% of oxygen results in a nonlinear superelastic behavior with small hysteresis and an increased yield stress. The stress-induced phase transformation in the Ti–25Nb–1O SMA is hindered due to the addition of oxygen interstitials. The difference between the deformation mechanisms and the resulting mechanical behaviors of the SMAs was clearly reflected by the recorded AE signals and deformation fields. It was shown that the AE can serve to track the development of the stress–induced phase transformations in the Ti–25Nb and Ti–25Nb–1O SMAs during tension. The AE signals were correlated to the strain fields of the SMAs, which showed a Lüders–type deformation of the Ti–25Nb SMA and a distinct but still inhomogenous deformation of the Ti–25Nb–1O SMA. The results of this study show that DIC and AE techniques are effective tools for monitoring phase transformations of the Ti–25Nb and Ti–25Nb–1O SMAs during tensile loading Keywords:
Shape memory alloys, Oxygen interstitials, Martensitic transformation, Acoustic emission, Digital image correlation Affiliations:
| Golasiński K. | - | other affiliation | | Brodecki A. | - | IPPT PAN | | Ranachowski Z. | - | IPPT PAN | | Tasaki W. | - | other affiliation | | Pieczyska E. | - | IPPT PAN | | Kim H. | - | other affiliation |
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| 3. |
Golasiński K.♦, Maj M., Musiał S., Tasaki W.♦, Kim H.♦, Use of Infrared Thermography for Inspection of Tensile Deformation of Ti-25Nb-0.5O and Ti-25Nb-0.5N Shape Memory Alloys,
Proceedings — Open Access Journal, ISSN: 2504-3900, DOI: 10.3390/proceedings2025129076, Vol.129(1), No.76, pp.1-4, 2025Keywords:
shape memory alloys, interstitials, infrared thermography, digital image correlation Affiliations:
| Golasiński K. | - | other affiliation | | Maj M. | - | IPPT PAN | | Musiał S. | - | IPPT PAN | | Tasaki W. | - | other affiliation | | Kim H. | - | other affiliation |
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| 4. |
Golasiński K.♦, Maj M., Tasaki W.♦, Pieczyska E.A., Kim H.♦, Full-Field Deformation Study of Ti–25Nb, Ti–25Nb–0.3O and Ti–25Nb–0.7O Shape Memory Alloys During Tension Using Digital Image Correlation,
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, ISSN: 1073-5623, DOI: 10.1007/s11661-024-07414-8, pp.1-10, 2024Abstract:
A Ti–25Nb shape memory alloy (SMA) exhibits shape memory effect associated with stress-induced martensitic transformation from β to α″ phase. Addition of oxygen stabilizes the β phase and changes stress–strain response. Oxygen-added Ti–25Nb SMAs show a more distinct superelastic behavior. In this work, digital image correlation (DIC) was applied to investigate for the first time full-field deformation of Ti–25Nb, Ti–25Nb–0.3O and Ti–25Nb–0.7O (at. pct) SMAs. The specimens were subjected to loading–unloading tensile tests to study local and global mechanical characteristics related to activity of particular deformation mechanisms of the SMAs. Strain and strain rate fields were quantitatively compared at selected stages of each SMA’s deformation. It was found that the Ti–25Nb SMA exhibits a macroscopically localized Lüders-type deformation associated with the stress-induced phase transformation, whereas Ti–25Nb–0.3O and Ti–25Nb–0.7O SMAs show more discrete types of deformation related to activity of interstitial oxygen atoms. As a consequence, at particular stages of deformation, local values of strain rate of Ti–25Nb SMA were significantly higher than those of average strain rate. The results obtained in this paper provide a better understanding of the deformation mechanism in the oxygen-added Ti–25Nb based SMAs. Affiliations:
| Golasiński K. | - | other affiliation | | Maj M. | - | IPPT PAN | | Tasaki W. | - | other affiliation | | Pieczyska E.A. | - | IPPT PAN | | Kim H. | - | other affiliation |
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