Customization of NiTi(X,Y) Shape Memory Alloys for Elastocaloric Applications
Abstract: NiTi-Shape Memory Alloys are mostly used for applications in medical devices or actuator systems. The emerging field of elastocalorics combines many of the requirements of both existing technologies. With the potential of both helping to make cooling and heating more sustainable and at the same time multiplying the world’s market of Shape Memory alloy production, it is a very interesting field to be active in as an SMA producer. The existing alloys are not really the best fit for Elastocalorics, and therefore, there is a need for customized Shape Memory Alloys. Hysteresis, the material’s COP (Coefficient of performance), and cyclic stability are among the most important requirements. For cascaded systems, also precisely controlled alloy variations with close sequences of changing Af-temperatures. In this work, we present our recent results on the processing, training, and characterization of binary and quaternary alloys, wire, and sheet/ribbon for elastocaloric applications.
Effects of Direct Aging Heat Treatments on the Superelasticity of Nitinol Produced via L-PBF
Abstract: Nitinol (NiTi) alloy is widely recognized as a popular shape memory material, used in various biomedical and engineering applications. Recent research has focused on producing NiTi biomedical devices using laser powder bed fusion (L-PBF). Achieving superelasticity is essential for most NiTi components, especially for endovascular surgeries (e.g., stents), and is typically obtained through heat treatments. Given the differences between conventional and additive manufacturing (AM) methods, many studies aim to optimize heat treatments for AM parts. However, few studies explore direct aging, where aging is performed without prior solution annealing. This presentation covers recent findings on the effects of short-time direct aging heat treatments on the mechanical properties and microstructure of AM NiTi alloy. The results revealed high cyclic stability and superelastic recovery up to 10% deformation in direct-aged alloys, suggesting that solution treatment may not be necessary to achieve superelasticity, demonstrating the effectiveness of direct aging.
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