Single-phase high- and medium-entropy alloys with face-centred cubic (fcc) structure can exhibit high tensile ductility^1,2 and excellent toughness^2,3, but their room-temperature strengths are low^1,2,3. Dislocation obstacles such as grain boundaries⁴, twin boundaries⁵, solute atoms⁶ and precipitates^7,8,9 can increase strength. However, with few exceptions^8,9,10,11, such obstacles tend to decrease ductility. Interestingly, precipitates can also hinder phase transformations^12,13. Here, using a model, precipitate-strengthened, Fe–Ni–Al–Ti medium-entropy alloy, we demonstrate a strategy that combines these dual functions in a single alloy. The nanoprecipitates in our alloy, in addition to providing conventional strengthening of the matrix, also modulate its transformation from fcc-austenite to body-centred cubic (bcc) martensite, constraining it to remain as metastable fcc after quenching through the transformation temperature. During subsequent tensile testing, the matrix progressively transforms to bcc-martensite, enabling substantial increases in strength, work hardening and ductility. This use of nanoprecipitates exploits synergies between precipitation strengthening and transformation-induced plasticity, resulting in simultaneous enhancement of tensile strength and uniform elongation. Our findings demonstrate how synergistic deformation mechanisms can be deliberately activated, exactly when needed, by altering precipitate characteristics (such as size, spacing, and so on), along with the chemical driving force for phase transformation, to optimize strength and ductility.

具有面心立方 (fcc) 结构的单相高和中熵合金可以表现出高拉伸延展性^1,2和出色的韧性^2,3，但它们的室温强度较低^1,2,3。^晶界4、孪晶界⁵、溶质原子⁶和析出物^7、8、9等位错障碍物可以提高强度。然而，除了少数例外^8,9,10,11外，此类障碍物往往会降低延展性。有趣的是，沉淀物也会阻碍相变^12,13. 在这里，我们使用沉淀强化的 Fe-Ni-Al-Ti 中等熵合金模型，展示了一种将这些双重功能结合在单一合金中的策略。我们合金中的纳米析出物除了提供基体的常规强化外，还调节其从 fcc-奥氏体向体心立方 (bcc) 马氏体的转变，限制其在淬火通过转变温度后保持亚稳态 fcc。在随后的拉伸测试中，基体逐渐转变为 bcc-马氏体，从而显着提高强度、加工硬化和延展性。这种纳米沉淀物的使用利用了沉淀强化和相变诱导塑性之间的协同作用，从而同时提高了拉伸强度和均匀伸长率。