Laser Powder Bed Fusion of NiTi multimaterial for Integrating Shape Memory Effect and Superelasticity

The fabrication of complex smart structures is challenging for the design and realization of advanced devices in different applicative sectors, like aerospace, automotive, biomedical, where actuators, sensors and flexible elements are needed. While Additive Manufacturing allows to fabricate 3D structures with a high level of design complexity, the use of functional metallic materials, like Shape Memory Alloys (NiTi alloys), offers unique opportunities in advanced performances. In this work at first the fabrication of high quality multi-material lattice structures, based on the use of Ti-rich and Ni-rich NiTi, by Laser Powder Bed Fusion, was shown. The functional testing of such 3D structures was explored via differential scanning calorimetry and thermos-mechanical testing, coupled with microstructural investigation. It was found that the fabricated multi-material NiTi structures can offer tailored functional properties in a wider range of temperature, integrating the well-known shape memory and superelastic performance within a unique structure. Peculiar focus was carried out on the characterisation of the transient region between the two compositions, in terms of residual defects and chemical composition. This work open new challenges in the design and manufacturing of smart devices with enhanced performances.

Keywords: NiTi, Multimaterial, Shape memory effect, Superelasticity, Laser Powder Bed Fusion.

Reference: Aamer Nazir, Ozkan Gokcekaya, Kazi Md Masum Billah, Onur Ertugrul, Jingchao Jiang, Jiayu Sun, Sajjad Hussain, Multi-material additive manufacturing: A systematic review of design, properties, applications, challenges, and 3D printing of materials and cellular metamaterials, Materials & Design 226 (2023) 111661. DOI: https://doi.org/10.1016/j.matdes.2023.111661.