Dissimilar laser welding of NiTi to Ti6Al4V - weldability issues and their mitigation.

J.P. Oliveira, B. Panton, Z. Zeng,C. M Andrei, Y. Zhou, R.M. Miranda, F.M. Braz Fernandes

aCENIMAT/I3N, Dep. of Materials Science, FCT, Universidade Nova de Lisboa, Caparica, Portugal

bCentre for Advanced Materials Joining, University of Waterloo, Canada

cSchool of Mechanical, Electronic, and Industrial Engineering, University of Electronic Science and Technology of China, China

dCanadian Center for Electron Microscopy, Brockhouse Institute for Materials Research, McMaster University, Canada

eUNIDEMI, FCT, Universidade Nova de Lisboa, Caparica, Portugal

Laser welding of NiTi to Ti6Al4V by fusion-based methods is difficult owing to the formation of brittle intermetallic compounds. To overcome such problem the use of interlayers is of interest. In this work, a Nb interlayer was used to prevent mixing between NiTi and Ti6Al4V during laser welding. Advanced microstructural characterization via scanning and transmission electron microscopy, nanoindentation and synchrotron X-ray diffraction was used to understand the joining mechanisms and microstructural evolution.