Microstructure and strengthening mechanisms of tantalum prepared using laser melting deposition.

Laser melting deposition (LMD) additive manufacturing process has been attractive to the fabrications of pure tantalum due to the advantage of fast near net shaping of complex shaped components. In the present study, the LMD process has been applied to the fabrication of tantalum using two kinds of powders with different interstitial contents. The microstructure, chemistry, and mechanical properties of the LMD samples have been investigated to understand the strengthening mechanisms. The results show that the tantalum samples have near full dense, and large columnar grains with the growth direction slightly deviated from the deposition direction. The LMD tantalum can have high hardness of up to 300 HV, mainly due to the solid solution strengthening of nitrogen and oxygen interstitials. With relative low interstitial contents of about 400 ppm, the LMD tantalum can have ductile properties, showing ultimate tensile strength above 400 MPa, and elongations of about 14–16%, which are comparable to the properties of cold-worked tantalum. The present work suggests the LMD tantalum could have potential usages in the industry fields. • Near full dense pure tantalum has been fabricated by laser melting deposition. • The tantalum has large epitaxially grown columnar grains. • Solid solution strengthening of interstitials lead to high hardness and high strength. [ABSTRACT FROM AUTHOR]