Metastable high entropy alloys (HEAs) have attracted extensive attention due to their excellent combination of high strength and great plasticity. In this work, we utilize constraining effects to tailor phase transformation strengthening and plasticity of nanostructured HEA (FeCoCrNi) thin films prepared by the magnetron sputtering technique via HEA/Cu and HEA/Ni nanotwinned nanolaminates (NTNLs). It is uncovered that the HEA/Cu NTNLs without phase transformation exhibit the fashion of “smaller is stronger” and HEA layers become more favorable to detwin at a smaller layer thickness (h). By contrast, the HEA/Ni NTNLs manifest an ultra-high peak hardness plateau accompanied by the FCC-to-HCP phase transformation in HEA layers at large h ≥ 25 nm, whereas they manifest size-dependent hardness when detwinning occurs at smaller h. This unusual plastic deformation behavior of HEA/X (X = Cu, Ni) NTNLs was rationalized by partial-based mechanisms. These findings open a new avenue to achieve superior mechanical properties of HEAs particularly at the nanoscale.

中文翻译：

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定制相变强化和纳米结构高熵合金的可塑性。

亚稳高熵合金（HEA）由于其高强度和高塑性的出色结合而受到广泛关注。在这项工作中，我们利用约束效应来调整通过磁控溅射技术通过HEA / Cu和HEA / Ni纳米孪晶纳米层压材料（NTNLs）制备的纳米结构HEA（FeCoCrNi）薄膜的相变强化和可塑性。已经发现，没有相变的HEA / Cu NTNL表现出“越小越强”的方式，并且HEA层变得更有利于在较小的层厚度（h）下相互缠绕。相比之下，HEA / Ni NTNLs表现出超高的峰值硬度平稳期，并伴随着在大h时HEA层中从FCC到HCP的相变。≥25 nm，而当在较小的h发生解缠时，它们表现出与尺寸有关的硬度。HEA / X（X = Cu，Ni）NTNLs的这种异常的塑性变形行为通过基于部分的机制得以合理化。这些发现为实现HEA的优异机械性能开辟了新途径，尤其是在纳米级。