Cold gas-dynamic spray or, more commonly, cold spray (CS) technology has opened a new avenue for additive manufacturing (AM) of metallic material. AM of refractory metals, such as tantalum (Ta), is highly valued due to its wide application in different industrial sectors. The CS process offers several advantages compared with laser-based, or melt-driven metal AM processes, such as shorter manufacturing times, practically unlimited bulk component size, and more excellent material selection flexibility. More importantly, CS’s solid-state nature is an attractive AM method for high melting temperature refractory metal AM, including Ta. In this research, we presented the capability of the CS process as a method for AM of Ta. Following the successful manufacturing of free-standing Ta, an extensive mechanical characterization at the macro and nano levels has been carried out to evaluate the material’s structural integrity. Anisotropy in the mechanical properties, which is one of the major concerns in the AM-produced materials, was extensively analyzed at the macro and nano levels. The produced Ta’s resistance against the pre-existing crack was studied by evaluating the far-field J-integral versus the crack extension (J-R curve). The influence of microstructural characteristics and process-induced defects such as pores and micro-cracks on the Ta’s mechanical and fracture properties was studied to explain the performance-microstructure linkage. The mechanical testing results indicated an elastic modulus and ultimate tensile strength in the range of conventionally produced Ta ingots following cold-working. Moreover, excellent isotropy in the mechanical properties was observed at both the macro and nano levels. This finding distinguishes the CS process from the laser-based AM process in which mechanical properties highly depend on the build direction. On the other hand, the CS-produced Ta exhibited brittle characteristics during uniaxial tensile loading and ductile behavior during the uniaxial compression test. The results of this research are accessible in the public domain.
Researcher: Dr. Davoud Mashhadijafarlou
