The aim of this project was to study two strategies of joining SMAs in similar and dissimilar (AISI316L and Ti6Al4V) joints: one using a Nd/YAG laser to weld micro parts of NiTi, investigating the process and the effect of laser beam collimated radiation on the extent of induced transformations; another using a femtosecond laser to ignite coated components with Ni/Ti and Pd/Al self-propagating reactive multilayer thin films with nanometric periods. The Ni/Ti multilayers were chosen as they react to form the SMA alloy which will be joined, while the Pd/Al multilayers were selected due to their high energy of reaction. The two procedures envisaged establishing the boundaries of applicability (technological and economical) which can potentiate new applications of SMAs in micro components or in larger ones, but within a small scale. The joints were fully characterised to establish the best joining strategy for micro to small scale systems manufacturing.
Partners: FCTUNL, FCTUC, IST, FEUP, UNIDEMI, CENIMAT
Funding organization: Science and Technology Foundation (PT)
Main achievements: Considerable knowledge was acquired in two main areas: - production of joints between NiTi to NiTi and NiTi to Ti6Al4V and AISI 316L with Nd/YAG and femtosecond lasers and by multi reactive nanometric layers deposited by sputtering - nanostructural and mechanical characterization of the joints including evaluation of the shape memory effect. Joining of NiTi to NiTi is feasible by the tested methods while dissimilar joining is more complex and the major constrains were Identified.