Textural Modifications during Recovery in Ti-Rich Ni-Ti Shape Memory Alloy Subjected to Low Level of Cold Work Reduction

摘要

In shape memory alloys (SMA), the texture can be an interesting factor influencing the anisotropic physical and mechanical characteristics during the phase transformations. It is well known that the texture significantly influences the stress-strain curve and shape memory strain of NiTi SMA. The aim of the present experiment was to analyze the textural modifications in the Ti-rich Ni-Ti SMA after annealing at moderate (500°C for 30 min) and subsequent low level of cold work reduction (10% thickness reduction). The textural results were obtained by X-Ray Diffraction (XRD) during thermal cycling in three points: (ⅰ) at room temperature (B19' phase, after cold work), (ⅱ) at 180°C (B2 phase), and (ⅲ) at room temperature (B19' phase, after cooling from 180°C). The phase transformations were characterized by Differential Scanning Calorimetry (DSC) and XRD.