Oxygen solute strengthening is an effective strategy to harden alloys, yet, it often deteriorates the ductility. Ordered oxygen complexes (OOCs), a state between random interstitials and oxides, can simultaneously enhance strength and ductility in high-entropy alloys. However, whether this particular strengthening mechanism holds in other alloys and how these OOCs are tailored remain unclear. Herein, we demonstrate that OOCs can be obtained in bcc (body-centered-cubic) Ti-Zr-Nb medium-entropy alloys via adjusting the content of Nb and oxygen. Decreasing the phase stability enhances the degree of (Ti, Zr)-rich chemical short-range orderings, and then favors formation of OOCs after doping oxygen. Moreover, the number density of OOCs increases with oxygen contents in a given alloy, but adding excessive oxygen (>3.0 at.%) causes grain boundary segregation. Consequently, the tensile yield strength is enhanced by ~75% and ductility is substantially improved by ~164% with addition of 3.0 at.% O in the Ti-30Zr-14Nb MEA.

氧溶质强化是硬化合金的有效策略，但它通常会降低延展性。有序氧络合物 (OOC) 是介于随机填隙原子和氧化物之间的一种状态，可以同时提高高熵合金的强度和延展性。然而，这种特殊的强化机制是否适用于其他合金以及如何定制这些 OOC 仍不清楚。在此，我们证明了可以通过调整 Nb 和氧的含量在 bcc（体心立方）Ti-Zr-Nb 中熵合金中获得 OOC。降低相稳定性会提高富含 (Ti, Zr) 的化学短程有序度，然后有利于掺杂氧后 OOC 的形成。此外，OOCs 的数密度随着给定合金中氧含量的增加而增加，但添加过量的氧（>3.0 大气压）。%)导致晶界偏析。因此，通过在 Ti-30Zr-14Nb MEA 中添加 3.0 at.% O，拉伸屈服强度提高了约 75%，延展性显着提高了约 164%。