Microstructure and mechanical properties of a refractory Ti–Nb–Zr complex concentrated alloy produced by laser-based directed energy deposition (DED-LB)

This study investigates the microstructure and mechanical properties of a refractory Ti₂NbZr complex concentrated alloy fabricated for the first time by laser-based directed energy deposition (DED-LB) from a pre-alloyed powder. The optimal processing parameters were identified; specifically, a laser power of 1600 W ensured a minimum porosity of 0.031 %. Comprehensive analysis revealed the formation of a single-phase BCC structure with a heterogeneous morphology, in which large columnar grains alternated with layers of fine equiaxed grains. The average grain size decreased with increasing specimen height. Mechanical testing demonstrated a favorable combination of strength and ductility, with a yield strength of ~810 MPa, an ultimate tensile strength of ~815 MPa, and an elongation of 16 %. A theoretical assessment of the contributions of the strengthening mechanisms showed good agreement with the experimental data. Solid-solution strengthening was found to make the dominant contribution to the alloy strength. The results confirm the potential of DED-LB for manufacturing high-quality Ti₂NbZr components with mechanical properties superior to those of counterparts produced by conventional and additive technologies.

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