Cracking suppression in selective electron beam melted WMoTaNbC refractory high-entropy alloy

WMoTaNb refractory high-entropy alloy (RHEA) with its brilliant thermal resistance at 1600 ℃ becomes increasingly attractive to researchers. To accelerate the processing stage of WMoTaNb RHEA before fulfilling diverse demands, additive manufacturing was employed for fabricating WMoTaNb RHEA. However, recent study of the additively manufactured WMoTaNb RHEA frequently encountered serious cracking behavior, which hinders the potential development of this alloy. In an attempt to mitigate such cracking behavior, graphite with a concentration of 0.5 wt% (5.43 at%) was introduced to modify the microstructure in the as-deposited WMoTaNbC RHEA. The experimental results revealed that C is responsible for prolonged solidification range and small quantity of eutectic reaction into WMoTaNb RHEA, which caused formation of dense dendrites and posed significant effect on lowering the cracking susceptibility. Such an effect of cracking suppression positively provides a new window for fabrication of refractory alloys in high quality with additive manufacturing.