Modeling and experimental validation of additively manufactured tantalum-titanium bimetallic interfaces

Bimetallic structures processed via laser-based additive manufacturing (AM) efficiently combine multiple materials in single components, which are difficult to achieve using traditional methods. However, limited understanding exists on how processing parameters influence the resulting microstructures and thermal profiles of base material during processing, affecting component performance. To this end, we present a combined numerical and experimental study on the effects of input laser power and scanning speed on the heat-affected-zone (HAZ) and fusion-zone (FZ) of a tantalum-titanium bimetallic structure, two compatible materials that are challenging to process traditionally and are desirable in a bimetallic system. We demonstrate that a wide array of track characteristics can be achieved by varying the laser power and scanning speed. The HAZ and FZ microstructures' width and depth within the underlying Ti6Al4V substrate can be estimated within 6–19% of the experimentally determined values using a 3D transient-thermal finite element analysis (FEA) model, with the most significant errors occurring at low scanning speeds. Adjusting the absorptivity input to the model improves prediction to within 1–11% difference of the HAZ/FZ dimensions and corresponding temperatures relative to the experimental dimensions across a broad range of laser power and scanning speeds. Our results indicate that the underlying temperatures achieved in bimetallic components can be predicted accurately using a detailed FEA approach, aiding larger-scale approaches towards improved process modeling and manufacturing of bimetallic structures using laser-based AM.