Heterogeneous microstructure alloys provide a possibility for the combination of strength and ductility. As a typical heterogeneous microstructure, partially recrystallized microstructure is attractive because of the convenient processing route and great potential for industrial applications. However, the mechanical properties of this microstructure vary dramatically with different morphology factors, especially the recrystallization fraction, which restricts the processing window and the property consistency. In this study, we found that the yield strength (∼1.3 GPa) and ductility (∼20 %) of the partially recrystallized NiCoCrFeTiAl do not change when the recrystallization fraction increases from 21 % to 72 %. This novel phenomenon is attributed to an additional hetero-deformation induced (HDI) strain hardening effect produced by heterogeneous precipitates. With the increased recrystallization fraction, this additional HDI stress keeps the ductility unchanged by offsetting the decreased HDI stress arising from the hetero-deformation between recrystallized (RX) and non-recrystallized (NRX) areas. The unchanged yield strength comes from the increased strengthening effects of the lamellar precipitates and grain boundaries. We also confirmed that the discontinuous coarsening contributes to the formation of heterogeneous precipitates. These findings would open a new pathway for enhancing the consistency and processability of hetero-structured alloys and thus promote their broader industrial applications.

中文翻译：

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不连续粗化导致不同再结晶体积分数高熵合金的拉伸性能不变

异质微结构合金为强度和延展性的结合提供了可能。作为一种典型的异质显微组织，部分再结晶显微组织因其方便的加工路线和巨大的工业应用潜力而备受关注。然而，这种微观结构的力学性能随形貌因素的不同而变化很大，特别是再结晶分数，限制了加工窗口和性能一致性。在这项研究中，我们发现当再结晶分数从 21% 增加到 72% 时，部分再结晶 NiCoCrFeTiAl 的屈服强度 (∼1.3 GPa) 和延展性 (∼20%) 没有变化。这种新现象归因于异质沉淀物产生的额外异质变形诱导（HDI）应变硬化效应。随着再结晶分数的增加，这种额外的 HDI 应力通过抵消再结晶 (RX) 和非再结晶 (NRX) 区域之间的异质变形而降低的 HDI 应力，从而保持延展性不变。屈服强度不变来自于层状析出物和晶界强化效应的增强。我们还证实，不连续粗化有助于异质沉淀物的形成。这些发现将为提高异质结构合金的一致性和可加工性开辟一条新途径，从而促进其更广泛的工业应用。