Mechanical properties and microstructural characteristics of additively manufactured C103 niobium alloy

Abstract C103 is a refractory-based niobium alloy for high temperature applications in aerospace. This paper aims to evaluate the compatibility of C103 alloy as a choice of material for laser-based additive manufacturing (AM) technologies. Crack free AM specimens with relative densities of greater than 99% were successfully fabricated via laser powder bed fusion (L-PBF) method with horizontal and vertical build orientations. Static strength levels of the stress-relieved specimens exceeded that of their wrought counterparts. Higher yield and ultimate tensile strength of AM specimens were attributed to high dislocation density and the formation of dislocation cell structures, which was revealed by transmission electron microscopy. Loss of ductility in AM specimens was partially due to high density of dislocations (i.e., shorter mean free path for dislocations), while the presence of defects may also have compromised the total elongation to failure. Electron backscattered diffraction analysis revealed formation of sharp 001 | | B D rod texture in AM samples, which resulted in anisotropic mechanical behavior. Uniaxial tensile and compressive deformation led to the development of (001) parallel to tensile direction and parallel to build direction, respectively.