Influence of laser processing parameters on the density-ductility tradeoff in additively manufactured pure tantalum

Additive manufacturing (AM) has transformed the process of shaping refractory metals into complex form factors. This study was undertaken to investigate the AM processing parameters for pure tantalum (Ta) and to understand their influence on the attendant properties. Computational fluid dynamics simulations informed a subset of AM laser parameters that were manufactured and characterized for their porosity and mechanical response. Manufacturing with high energy densities (350-470 J/mm3) increased material density and mechanical strength, but dramatically reduced the ductility owing to the prolific formation of pre-existing edge cracks. While low porosity is typically a key metric for success in AM, the results presented here elucidate that a balance between maximizing bulk material density and minimizing steep thermal gradients during processing is needed to optimize the strength-ductility tradeoff.