School of Materials Science and Engineering, Beijing Institute of Technology, 100081, Beijing, China.
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China.
Nat Commun. 2018 Oct 3;9(1):4063. doi: 10.1038/s41467-018-06600-8.
Precipitation-hardening high-entropy alloys (PH-HEAs) with good strength-ductility balances are a promising candidate for advanced structural applications. However, current HEAs emphasize near-equiatomic initial compositions, which limit the increase of intermetallic precipitates that are closely related to the alloy strength. Here we present a strategy to design ultrastrong HEAs with high-content nanoprecipitates by phase separation, which can generate a near-equiatomic matrix in situ while forming strengthening phases, producing a PH-HEA regardless of the initial atomic ratio. Accordingly, we develop a non-equiatomic alloy that utilizes spinodal decomposition to create a low-misfit coherent nanostructure combining a near-equiatomic disordered face-centered-cubic (FCC) matrix with high-content ductile NiAl-type ordered nanoprecipitates. We find that this spinodal order-disorder nanostructure contributes to a strength increase of ~1.5 GPa (>560%) relative to the HEA without precipitation, achieving one of the highest tensile strength (1.9 GPa) among all bulk HEAs reported previously while retaining good ductility (>9%).
沉淀强化高熵合金（PH-HEAs）具有良好的强韧性平衡，是先进结构应用的有前途的候选材料。然而，目前的 HEAs 强调近等原子初始组成，这限制了与合金强度密切相关的金属间化合物析出相的增加。在这里，我们提出了一种通过相分离设计具有高含量纳米析出相的超强 HEAs 的策略，该策略可以在原位生成近等原子的基体，同时形成强化相，从而产生 PH-HEA，而与初始原子比无关。因此，我们开发了一种非等原子合金，利用旋节分解来创建一种低失配的共格纳米结构，该结构结合了近等原子无序面心立方（FCC）基体和高含量韧性 NiAl 型有序纳米析出相。我们发现，这种旋节有序-无序纳米结构有助于强度提高约 1.5 GPa（>560%），与没有析出相的 HEA 相比，实现了之前报道的所有块状 HEAs 中最高的拉伸强度之一（1.9 GPa），同时保持了良好的延展性（>9%）。
