Functional Shape Recovery Response of Heat-Treated NiTiCu SHAPE Memory Alloy Wire

Abstract

NiTiCu shape memory alloy wires are promising functional materials for applications requiring controlled deformation and shape recovery. In this study, the functional shape recovery response of a commercial 0.5 mm diameter NiTiCu wire was investigated after heat treatment at 450 °C for different durations. The untreated wire and the wires heat-treated for 30 and 60 min in sealed quartz tubes were comparatively evaluated. Differential scanning calorimetry was used as an auxiliary characterization method to determine the appropriate temperature for the recovery test rather than as the main basis of discussion. The DSC results showed that heat treatment shifted the transformation temperatures to higher values and narrowed the transformation intervals. Based on the Af temperatures, bend and free recovery tests were carried out at 55 ± 2 °C. The recovery behavior was evaluated after five repeated bending and free recovery measurements for each condition. The untreated sample showed a high recovery ratio of 98.7 ± 0.1%, while the values increased to 99.5 ± 0.3% and 99.75 ± 0.1% after 30 and 60 min of heat treatment, respectively. These results indicate that heat treatment at 450 °C preserved the functional recovery capability of the NiTiCu wire and slightly improved its bending-related shape recovery response, with the best performance obtained after 60 min of heat treatment.

Keywords

• NiTiCu wire
• Shape memory alloy
• Heat treatment
• Functional shape recovery
• Recovery ratio

Ethical Statement

Ethics committee approval was not required for this study because there was no study on animals or humans.

Thanks

The author would like to thank Dokuz Eylul University for providing laboratory facilities and technical support during the experimental studies.

References

1. Agarwal, N., Murphy, J. R., Hashemi, T. S., Mossop, T., O’Neill, D., Power, J., Shayegh, A., & Brabazon, D. (2023). Effect of heat treatment time and temperature on the microstructure and shape memory properties of Nitinol wires. Materials, 16(19), Article 6480. https://doi.org/10.3390/ma16196480
2. Apell, J., Rettenmayr, M., & Undisz, A. (2020). Evaluation methods for non-contact bend and free recovery tests of thin NiTi wires and their effects on measured transformation temperatures. Journal of Materials Engineering and Performance, 29(8), 5435–5441. https://doi.org/10.1007/s11665-020-05022-2
3. Askari-Naeini, F. G., Taghizadeh, M., Mohri, M., & Nili-Ahmadabadi, M. (2020). On the microstructure and mechanical properties of a two-way shape memory NiTi/NiTiCu bi-layer diaphragm. Materials & Design, 187, Article 108464. https://doi.org/10.1016/j.matdes.2019.108464
4. ASTM International. (2023). ASTM F2082/F2082M-23: Standard test method for determination of transformation temperature of nickel-titanium shape memory alloys by bend and free recovery. ASTM International.
5. Bogue, R. (2014). Smart materials: A review of capabilities and applications. Assembly Automation, 34(1), 16–22. https://doi.org/10.1108/AA-10-2013-094
6. Cai, S., Schaffer, J. E., Shi, T., Gao, J., & Kadeřávek, L. (2024). Effect of Cu alloying and heat treatment parameters on NiTiCu alloy phase stability and constitutive behavior. Shape Memory and Superelasticity, 10(2), 460–472. https://doi.org/10.1007/s40830-024-00504-x
7. Chen, L., Oliveira, J. P., Yan, X., Pang, B., Ke, W., Shen, J., Teshome, F. B., Schell, N., Zhou, N., Peng, B., & Zeng, Z. (2024). Microstructure and phase transformation behavior of NiTiCu shape memory alloys produced using twin-wire arc additive manufacturing. Additive Manufacturing Frontiers, 3, Article 200132. https://doi.org/10.1016/j.amf.2024.200132
8. Dang, P., Zhou, Y., Pang, J., Ding, X., Sun, J., Lookman, T., & Xue, D. (2023). Achieving stable actuation response and elastocaloric effect in a nanocrystalline Ti₅₀Ni₄₀Cu₁₀ alloy. Scripta Materialia, 226, Article 115263. https://doi.org/10.1016/j.scriptamat.2022.115263

9. Degeratu, S., Rotaru, P., Manolea, G., Manolea, H. O., & Rotaru, A. (2009). Thermal characteristics of Ni–Ti SMA (shape memory alloy) actuators. Journal of Thermal Analysis and Calorimetry, 97(2), 695–700. https://doi.org/10.1007/s10973-009-0215-0
10. Doğdu, N. (2026). Experimental and simulation-based assessment of dimensional accuracy and thermomechanical properties of AlSi10Mg cubes produced by LPBF. Materials & Design, 261, Article 115351. https://doi.org/10.1016/j.matdes.2025.115351
11. Drexel, M., Proft, J., & Russell, S. (2009). Characterization of transformation temperatures with the bend and free recovery technique: Parameters and effects. Journal of Materials Engineering and Performance, 18(5–6), 620–625. https://doi.org/10.1007/s11665-009-9434-6
12. Jani, J. M., Leary, M., Subic, A., & Gibson, M. A. (2014). A review of shape memory alloy research, applications and opportunities. Materials & Design, 56, 1078–1113. https://doi.org/10.1016/j.matdes.2013.11.084
13. Khalil-Allafi, J., Dlouhy, A., & Eggeler, G. (2002). Ni4Ti3-precipitation during aging of NiTi shape memory alloys and its influence on martensitic phase transformations. Acta Materialia, 50(17), 4255–4274. https://doi.org/10.1016/S1359-6454(02)00257-4
14. Koçkar Tuğla, R., Tavukçuoğlu, A., & Yazıcıoğlu, S. (2025). Development of a standard laboratory testing method for thermal diffusivity measurements of building walls: Combined use of infrared thermography and guarded hot box. Journal of the Faculty of Engineering and Architecture of Gazi University, 40(1),529–539. https://doi.org/10.17341/gazimmfd.1296046
15. Li, P., Wang, Y., Meng, F., Cao, L., & He, Z. (2019). Effect of heat treatment temperature on martensitic transformation and superelasticity of the Ti49Ni51 shape memory alloy. Materials, 12(16), Article 2539. https://doi.org/10.3390/ma12162539
16. Ma, J., Karaman, I., & Noebe, R. D. (2010). High temperature shape memory alloys. International Materials Reviews, 55(5), 257–315. https://doi.org/10.1179/095066010X12646898728363
17. Manjeri, R., Sczerzenie, F., & Coda, A. (2016). Uniaxial pre-strain and free recovery (UPFR) as a flexible technique for Nitinol characterization. Shape Memory and Superelasticity, 2(1), 86–94. https://doi.org/10.1007/s40830-015-0047-7
18. Memarian, M., Mohri, M., Golrang, M., Leinenbach, C., Ferretto, I., Ghafoori, E., & Nili-Ahmadabadi, M. (2024). Evaluation of interface and residual strain of NiTi layer deposited on NiTiX substrate by laser powder bed fusion. Advanced Engineering Materials, 26(11), Article 2400002. https://doi.org/10.1002/adem.202400002
19. Mohammed, S., Qadır, R., Kök, M., & Qader, I. (2021). A review on NiTiCu shape memory alloys: Manufacturing and characterizations. Journal of Physical Chemistry and Functional Materials, 4(2), 49–56. https://doi.org/10.54565/jphcfum.1018817
20. Mohd Jani, J., Leary, M., & Subic, A. (2017). Designing shape memory alloy linear actuators: A review. Journal of Intelligent Material Systems and Structures, 28(13), 1699–1718. https://doi.org/10.1177/1045389X16679296
21. Ninarello, D., Passaretti, F., & Nespoli, A. (2023). Body temperature NiTi alloys: Effect of the heat treatment on the functional thermo-mechanical properties. Journal of Thermal Analysis and Calorimetry, 148(20), 10757–10775. https://doi.org/10.1007/s10973-023-12437-1
22. Obaisi, N. A., Galang-Boquiren, M. T. S., Evans, C. A., Tsay, T. G. P., Viana, G., Berzins, D., & Megremis, S. (2016). Comparison of the transformation temperatures of heat-activated Nickel-Titanium orthodontic archwires by two different techniques. Dental Materials, 32(7), 879–888. https://doi.org/10.1016/j.dental.2016.03.017
23. Otsuka, K., & Ren, X. (1999). Recent developments in the research of shape memory alloys. Intermetallics, 7(5), 511–528. https://doi.org/10.1016/S0966-9795(98)00070-3
24. Otsuka, K., & Ren, X. (2005). Physical metallurgy of Ti–Ni-based shape memory alloys. Progress in Materials Science, 50(5), 511–678. https://doi.org/10.1016/j.pmatsci.2004.10.001
25. Pelton, A. R., DiCello, J., & Miyazaki, S. (2000). Optimisation of processing and properties of medical grade Nitinol wire. Minimally Invasive Therapy & Allied Technologies, 9(2), 107–118. https://doi.org/10.3109/13645700009063057
26. Scholtes, D., Seelecke, S., & Motzki, P. (2024). Electro-thermo-mechanical characterization of shape memory alloy wires for actuator and sensor applications—Part 1: The effects of training. Engineering Reports, 6(10), Article e12867. https://doi.org/10.1002/eng2.12867
27. Sehitoglu, H., Hamilton, R., Maier, H. J., & Chumlyakov, Y. (2004). Hysteresis in NiTi alloys. Journal de Physique IV France, 115, 3–10. https://doi.org/10.1051/jp4:2004115001
28. Zeybek, Ü. (2025). Mechanically alloyed Zr-doped NiTi powders: A study on R-phase formation and austenitic transformation behaviour. Canadian Metallurgical Quarterly. Advance online publication. https://doi.org/10.1080/00084433.2025.2575229