Dual-phase high-entropy alloys (DP-HEAs), characterized by an alternation of soft and hard phases, are expected as promising candidates for structural applications, owing to their remarkable combination of high strength and ductility. However, the role of phase interfaces in the dynamic deformation of these nano lamellar systems remains poorly elucidated, primarily because of the challenges pertinent to real-time characterization at nanoscopic resolutions. Here, the intricate interplay between shock waves and phase interfaces in face/body-centered cubic (FCC/BCC) FeCoNiCu_xAl_1-x HEA nanolaminates was examined, through performing large-scale molecular dynamics (MD) simulations. As a consequence of stress concentration at interfaces, shock waves with intensities beneath the Hugoniot elastic limit (HEL) were confirmed to trigger dislocation at these interface sites. These dislocations slipped in directions counter to that of deformation-induced ones, making them susceptible to collisions and subsequent dislocation reactions, which effectively fostered the emergence of immobile Hirth dislocations and thus an additional strain-hardening effect. Meanwhile, the BCC phase was demonstrated to undergo deformation through a transformation into a hexagonal close-packed (HCP) structure upon exposure to shock waves, accompanied by twinning within emergent HCP lamellae. This would contribute to dissipating energy from the propagating shock waves. More interestingly, the magnitude of both phase transition and twinning can be dynamically manipulated through the strategic manipulation of Cu/Al compositional ratios in the BCC phase. In addition, the layer-thickness difference was corroborated to dramatically affect the dynamic deformation behavior of DP-HEA systems. A decrease in layer thickness allowed a more frequent interaction between shock waves and phase interfaces, alleviating stress concentration and encouraging greater plastic deformation. Our current study illuminates the dynamic deformation characteristics of DP-HEAs, offering pivotal insights that can design and develop HEAs with optimized properties for future applications.

中文翻译：

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FCC/BCC 高熵合金纳米层压板中的界面依赖性动态变形行为


双相高熵合金 （DP-HEAs） 的特点是软相和硬相交替，由于其高强度和延展性的显着结合，有望成为结构应用的有前途的候选者。然而，相界面在这些纳米层状系统的动态变形中的作用仍然难以阐明，这主要是因为在纳米级分辨率下进行实时表征存在相关挑战。在这里，通过进行大规模分子动力学 （MD） 模拟，检查了面/体心立方 （FCC/BCC） FeCoNiCu_xAl_1-x HEA 纳米层压板中冲击波和相位界面之间的复杂相互作用。由于界面处的应力集中，强度低于 Hugoniot 弹性极限 （HEL） 的冲击波被证实会触发这些界面部位的位错。这些位错沿与变形引起的位错相反的方向滑动，使它们容易受到碰撞和随后的位错反应的影响，这有效地促进了固定 Hirth 位错的出现，从而产生了额外的应变硬化效应。同时，BCC 相在暴露于冲击波后通过转变为六边形紧密堆积 （HCP） 结构而发生变形，并伴有新出现的 HCP 薄片内的孪生。这将有助于耗散传播的冲击波的能量。更有趣的是，相变和孪晶的大小都可以通过在 BCC 相中策略性地操纵 Cu/Al 组成比来动态操纵。此外，层厚差异被证实对 DP-HEA 系统的动态变形行为产生了显著影响。 层厚的减少允许激波和相界面之间更频繁地相互作用，从而减轻应力集中并促进更大的塑性变形。我们目前的研究阐明了 DP-HEA 的动态变形特性，为未来应用设计和开发具有优化特性的 HEA 提供了关键见解。