Powder production of an equimolar NbTaTiZr high-entropy alloy via hydrogen embrittlement

Powder metallurgy methods such as additive manufacturing are often employed to fabricate bulk refractory alloys with high-melting temperature, nevertheless, it still remains a challenge to produce high-quality refractory high-entropy alloy (RHEAs) powders. In this work, we found that hydrogen absorption can embrittle the NbTaTiZr RHEA and promote intragranular fracture due to segregation of hydrogen atoms at grain boundaries. Synergistic effects of the hydrogenation temperature and time on the pulverization behavior of the NbTaTiZr RHEA were investigated, and the relation between grain sizes in the original ingots and particle sizes in the pulverized powders was explored. The present findings not only provide a highly efficient approach to produce high-quality powders of alloys with high-melting points, but also shed light into understanding hydrogen embrittlement of RHEAs.