WE Colloquium: Joao Oliveira, Laser welding of shape memory alloys: strategies for dissimilar combinations

Abstract

The development of welding processes for joining of advanced materials is fundamental to expand the range of applications where such materials can be used. Laser welding is a high power density process widely used for advanced materials joining.

Shape memory alloys are a class of functional materials which find application in a variety of industries such as the biomedical, aerospace and automotive. Any of these industries would benefit of joining such materials to other relevant engineering materials. However, dissimilar joining involving shape memory alloys is often problematic due to the formation of brittle intermetallic compounds.

In this presentation, the first dissimilar laser joint between a NiTi shape memory and Ti6Al4V is presented. The process strategies used to overcome the formation of undesired compounds are discussed. Additionally, recent results on dissimilar laser welding of NiTi to a Cu-based alloy will be presented and discussed. Although Cu-based alloys are difficult to weld using conventional and industry relevant Nd:YAG lasers, it will be shown that the proper development of the laser welding process enables successful joining of these materials.

Bio

Joao Oliveira got his Ph.D. in Materials Science and Engineering at Universidade Nova de Lisboa, Portugal, where he specialized in the development of laser welding and laser processing strategies for advanced materials, such as shape memory alloys and high entropy alloys. His research work also encompassed the use of fusion-based methods (gas tungsten arc welding) and solid-state ones (friction stir welding and magnetic impulse welding) to join shape memory alloys in both similar and dissimilar combinations. Additionally, he has worked in additive manufacturing of high strength steels.

Currently, Joao is a postdoctoral researcher at the Welding Engineering Program at The Ohio State University where he is engaged in several projects related to advanced characterization and process development for different industries.

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