Dynamic mechanical response of TaMoNbZrTi refractory high entropy alloy via multi-wire arc additive manufacturing

Here, the TaMoNbZrTi refractory high entropy alloy (RHEA) is fabricated by multi-wire arc additive manufacturing (MWAAM), and the dynamic mechanical behaviour is analysed. A pre-alloyed droplet transfer mode is proposed to facilitate decent metallurgical reactions of different wire feedstocks, with the assistance of hot-wire and pulsed arc processing. The RHEA exhibits dendritic microstructures and consists of two Body-Centered-Cubic (BCC) phases. Dynamic compression testing suggests that as the strain rate increases from 920 to 4100 s−1, the yield strength of the RHEA is boosted by ∼158%, and the fracture strain increases by ∼72%. More dislocations appear at the Zr-Ti-rich interdendritic region with 4.0 × 1014 /m2 geometrically necessary dislocations (GND) density, compared with the dendrite with 2.1 × 1014 /m2 GND density, and they accumulate around the Ta-Mo-Nb-rich cellular particles. Our work provides an efficient pathway for the one-step additive manufacturing of RHEAs and makes a pioneering exploration of their microstructures and dynamic mechanical behaviour.