Shape memory alloys (SMAs) are a unique class of smart materials and they were employed in various applications in engineering, biomedical, and aerospace technologies. Here, we report an advanced, efficient, and low-cost direct imprinting method with low environmental impact to create thermally controllable surface patterns. Patterned microindents were generated on Ni50Ti50 (at. %) SMAs using an Nd:YAG laser with 1064 nm wavelength at 10 Hz. Laser pulses at selected fluences were focused on the NiTi surface and generated pressure pulses of up to a few GPa. Optical microscope images showed that surface patterns with tailorable sizes can be obtained. The depth of the patterns increases with laser power and irradiation time. Upon heating, the depth profile of SMA surfaces changed where the maximum depth recovery ratio of 30 % was observed. Recovery ratio decreased and saturated at about 15 % when the amount of time and thus the indent depth was increased. Laser-induced shock wave propagation inside the material was simulated and showed a good agreement with the experimental results. The stress wave closely followed the rise time of the laser pulse to its peak value and initial decay. Rapid attenuation and dispersion of the stress wave were observed.

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Published in Proceedings of SPIE, v. 10520, Laser-based Micro- and Nanoprocessing XII, article 105200V, p. 1-7.

© 2018 SPIE. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.

Saidjafarzoda Ilhom, Khomidkhodzha Kholikov, Peizhen Li, Dovletgeldi Seyitliyev, Zachary Thomas, Duvall Roberts, Omer San, Haluk E. Karaca, and Ali O. Er, "Formation of two-way shape memory effect in NiTi alloy using pulsed laser irradiation," Proc. SPIE 10520, Laser-based Micro- and Nanoprocessing XII, 105200V (February 19, 2018). DOI: https://doi.org/10.1117/12.2290276

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