Quad-heterostructure precipitation-strengthened high-entropy alloy overcomes strength-ductility trade-off from cryogenic to intermediate temperatures

We use a multi-heterostructure strategy to mitigate temperature-induced brittleness and strain-softening in precipitation-strengthened high-entropy alloys (PSHEAs). A PSHEA consisting of four types of heterostructures, including deformed/recrystallization grains bands inside with irregularly-shaped/spheroidal coherent precipitates, and smooth/serrated grain and precipitate-matrix interfaces, is successfully synthesized. The resultant PSHEA exhibits significantly-enhanced strength and uniform elongation simultaneously at −196–700 °C. This overcoming of the strength-ductility trade-off is attributed to a synergistic hetero-deformation-induced strengthening effect, and a two-level strain-delocalization toughening effect. Our findings offer a promising pathway to develop ultra-strong, ductile, and strain-hardenable PSHEAs and superalloys in a wide temperature range. A precipitation-strengthened high-entropy alloy consisting of four types of heterostructures is designed and investigated, achieving significantly-enhanced strength and uniform elongation simultaneously at −196–700 °C.

本研究采用多异质结构策略，以缓解析出强化高熵合金（precipitation-strengthened high-entropy alloys，PSHEAs）中的温度诱导脆性与应变软化问题。本研究成功合成了一种包含四类异质结构的PSHEA，其内部兼具变形/再结晶晶粒带、不规则形/球形共格析出相，以及光滑/锯齿状的晶粒界面与析出相-基体界面。所制备的该合金在-196℃至700℃的温度区间内，可同时实现强度与均匀延伸率的显著提升。这种对强度-塑性权衡瓶颈的突破，归因于协同的异质变形诱导强化效应与两级应变脱局域化增韧效应。本研究结果为在宽温度区间内开发超高强度、高塑性且具备应变硬化能力的PSHEAs与高温合金提供了极具前景的技术路径。本研究设计并研究了一类包含四类异质结构的析出强化高熵合金，该材料同样可在-196℃至700℃的温度区间内实现强度与均匀延伸率的同步显著提升。