Preliminary study on the thermomechanical treatment of shape memory alloys for applications in clothing protecting against heat

Nowadays, a rapid growth of smart materials' implementation in textiles and clothing can be observed as it allows attaining the functions and properties unachievable with conventional materials. Unique characteristics of shape memory alloys, in particular nickel-titanium (NiTi), place them in the focus of interest in this area. Despite numerous research works concerning the analysis of the NiTi alloys' properties, a further investigation is still needed due to their sensitivity to thermomechanical treatment conditions. In this article, the results of preliminary study aimed at designing thermomechanical treatment procedure for NiTi elements intended for specific application in clothing protecting against heat are presented. The analysis of the influence of annealing temperature and thermomechanical cycling method on characteristic temperatures of martensitic transformation with use of differential scanning calorimetry was performed. Moreover, recovery rate characterizing two-way shape memory effect was evaluated. Test results indicate that by means of an appropriate selection of the alloy and choice of thermomechanical treatment conditions, it is possible to achieve a phase transition in the required temperature range and desired recovery rate of NiTi elements.