PSI - Issue 69

Alberto Coda et al. / Procedia Structural Integrity 69 (2025) 26–34

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3. Conclusions In the present study the effect of Cu/Co addition to Ni 3 Ta and heat treatments were explored. Their effects on microstructure, microhardness and thermal transformation were measured. The following observations were made: • Thermal transformation of Ni 3 Ta is stable under cycling. Already after two thermal DSC cycles shift in transformation is negligible. • 1 at. % Cu and Co shifts transformation temperatures down. However, the temperatures remain significantly above binary NiTi transformation temperatures. • The investigated alloy properties remained almost unaffected by the explored heat treatments in the range of 1200 – 1350 °C for 4h. While the possibility of tailoring the microstructure by higher temperatures annealing is limited, the thermal stability could also represent an asset for the alloy application at elevated temperatures. Future investigations of these systems can consider higher additions of Cu and Co as well as aging treatments at low temperatures to induce within the matrix precipitates that can affect mechanical and transformation properties.Much work needs still to be done to further explore and understand the mechanical and shape memory recovery behavior of these high temperature transforming alloys. The authors wish to thank Eng. Paola Bassani, Eng. Sergio Arnaboldi, Mr Giordano Carcano, Mr Marco Pini and Mr Nicola Bennato for their appreciated support in the experimental phase. The work was development in the framework of “Mind in Italy” project and sponsored by Regione Lombardia. References [1] Chaudhari, R., Vora, J.J., Parikh, D.M. (2021). A Review on Applications of Nitinol Shape Memory Alloy. In: Parwani, A.K., Ramkumar, P., Abhishek, K., Yadav, S.K. (eds) Recent Advances in Mechanical Infrastructure. Lecture Notes in Intelligent Transportation and Infrastructure. Springer, Singapore. https://doi.org/10.1007/978-981-33-4176-0_10 [2] Firstov, G., et al. "Directions for High-Temperature Shape Memory Alloys’ Improvement: Straight Way to High-Entropy Materials, Shap. Mem. Superelasticity. 1 (2015) 400-407." 2015, [3] G.S. Firstov, J. Van Humbeeck, Yu.N. Koval, Comparison of high temperature shape memory behavior for ZrCu-based, Ti-Ni-Zr and Ti-Ni-Hf alloys, Scripta Materialia 50 (2004) 243-248. [4] Van Humbeeck, Jan. "Shape memory alloys with high transformation temperatures."Materials Research Bulletin 47.10 (2012): 2966-2968. [5] K. Wu, J.L. Ma, A review of high-temperature shape memory alloys, Proc. Of SMST (2000) 153-161. [6] Jani, Jaronie Mohd, et al. "A review of shape memory alloy research, applications and opportunities." Materials & Design (1980-2015) 56 (2014): 1078-1113. [7] Abubakar, Rabiu Ahmad, Fan Wang, and Linxiang Wang. "A review on Nitinol shape memory alloy heat engines." Smart Materials and Structures 30.1 (2020): 013001. [8] Tong, Yunxiang, Aleksandr Shuitcev, and Yufeng Zheng. "Recent development of TiNi‐based shape memory alloys with high cycle stability and high transformation temperature." Advanced Engineering Materials 22.4 (2020): 1900496. [9] Umale, T., Salas, D., Tomes, B., Arroyave, R., & Karaman, I. (2019). The effects of wide range of compositional changes on the martensitic transformation characteristics of NiTiHf shape memory alloys. Scripta Materialia, 161, 78-83. Acknowledgements