Research Article Effects of Predefined Thermomechanical Procedure on the MicrostructureandMechanicalPropertiesoftheTwo-WayShape Memory Effect in the NiTi Alloy Ali Tahaei , 1 Ali Aghajani , 1 Mahmoud Abbasi , 2 Behrouz Bagheri , 2 Mattia Merlin , 3 and Gian Luca Garagnani 3 1 Kharazmi University, Tehran, Iran 2 Amirkabir University of Technology, Tehran, Iran 3 University of Ferrara, Ferrara, Italy Correspondence should be addressed to Ali Aghajani; aghajani_a@yahoo.com Received 22 November 2022; Revised 8 April 2023; Accepted 20 May 2023; Published 7 June 2023 Academic Editor: Sachin Salunkhe Copyright © 2023 Ali Tahaei et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In the current paper, a predefned thermomechanical procedure has been applied to the two•way shape memory efect (TWSME) in a NiTi alloy to study the efect of two diferent applied load conditions on the induced martensitic state. Te microstructure of the strips was studied using optical microscopy (OM), scanning electron microscopy (SEM) ftted with an EDS microprobe, and microhardness tests at the end of both the training and thermal cycles. Inducing internal stresses along specifed directions during training cycles results in the formation of oriented martensitic variants rather than expected twinned martensitic variants upon cooling. It was found that the microstructure is made up of interlocking martensitic lathes, including the fne martensite colony next to the coarse martensite lathes. Furthermore, the results of the average hardness tests for bending at one point and three points were 241 and 247HV0.2, respectively. It was shown that only the cubic austenitic phase (B2) and the martensitic monoclinic phase (B19′) experience transformation. Te results reveal that homogeneous bending in three locations leads to achieving the best diference between high• and low•temperature curvatures after training. 1. Introduction Due to their combination of the shape memory efect (SME), superelasticity, biocompatibility, and high reliability, shape memory alloys (SMAs), particularly NiTi alloys, are regarded as smart materials for the development of new advanced devices [1]. Tese materials are characterized by the presence of two diferent phases, namely, austenite, stable at high temperatures, and martensite, stable at low temperatures [2]. Te shape memory efect is caused by the thermo•elastic martensitic transformation and the corresponding shape changes in the crystallographic lattice. Te shape memory efect should be improved by carefully studying and opti• mizing the chemical composition, annealing, and shape• setting treatments [3]. Tere are four transformation tem• peratures present in shape memory alloys. During cooling, austenite undergoes a forward transformation into mar• tensite, which starts at the martensitic start temperature (Ms) and ends at the martensitic fnish temperature (Mf). When heated, martensite undergoes a reverse trans• formation into austenite that starts at the austenitic start temperature (As) and ends at the austenitic fnish temper• ature (Af) [4]. Tese transformation temperatures range from absolute zero to around 100 ° C and are therefore suitable for a variety of near•ambient temperature applications. Numerous mechanical devices that rely on NiTi wires or strips to induce a particular actuation use the one•way shape memory efect (OWSME). Tis efect is the material’s ca• pacity to recover signifcantly from large deformations ex• perienced during heating above a critical temperature. Te OWSME has found uses in various applications, such as Hindawi Advances in Materials Science and Engineering Volume 2023, Article ID 1524836, 11 pages https://doi.org/10.1155/2023/1524836