Study on the influence of oxygen content evolution on the mechanical properties of tantalum powder fabricated by laser powder bed fusion

In this work, the influence of reuse times on the properties of tantalum powder and its laser powder bed fusion (LPBF) product was investigated. For this purpose, a batch of tantalum powder was reused up to 16 times, and the particle size distribution, flowability, surface topography, and other characteristics of the powder were studied after different reuse times. The mechanical properties of the finished product samples were also tested. Results from the powder reuse showed that the particle size distribution of tantalum powder changed from 30.1 μm to 33.8 μm, and the oxygen content increased from 310 ppm to 450 ppm. The density and fracture strain of tensile specimens decreased from 16.57 g/cm3 to 16.48 g/cm3 and from 37.9% to 11.6%, respectively. The ultimate tensile strength and microhardness decreased after reaching a peak, ranging from 504 MPa to 614 MPa, and 227 HV to 245 HV, respectively. In addition, it was found that the oxides were mainly tantalum pentoxide, along with monovalent and bivalent oxides. The change in tensile properties was likely related to the interstitial solution of oxygen atoms. This study provides a reference for the reusability of LPBF tantalum powder.