Microstructure tailoring to enhance strength and ductility in pure tantalum processed by selective laser melting

Obtaining pure tantalum sample with high strength and ductility through selective laser melting (SLM) process has become a significant challenge. In this study, a superior improved ductility (12%) of SLM processed pure tantalum sample with a comparable tensile strength (exceeds 750 MPa) using triple heat treatment was achieved. The gradual globularization of the columnar grains during annealing and the formation of dislocation slip result in the high tensile elongation. The maintenance of high strength is mainly attributed to the ultrafine cellular structures, the accumulation of dislocations and the precipitation of hexagonal close-packed (HCP) phase during tensile process. The present study will provide significant guidance for the SLM processed pure tantalum with high strength and ductility.