Abstract Metallic materials produced by additive manufacturing experience complex stress and thermal gyrations along the build direction. This has the potential to produce complicated heterogeneous microstructures that may exhibit a wide variety of mechanical properties. There remains a paucity of studies on the nature and the formation mechanisms of the microstructural heterogeneity and this limits our capability for microstructural design in additively manufactured metallic materials. Here, we present an electron microscopy-based investigation of a CrMnFeCoNi high-entropy alloy produced by selective laser melting. We have focussed on a systematic investigation of the microstructural evolution along the build direction. Our results reveal a remarkable hierarchy of microstructures, including the formation of nanocrystalline grains, elemental segregation and precipitation, cellular dislocation structures, deformation twinning, and deformation-induced phase transformation. Our research clarifies the relationships amongst different features, and provides guidance for future structural manipulation of materials produced by additive manufacturing.

中文翻译：

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循环快速热载荷对选择性激光熔化制备的 CrMnFeCoNi 高熵合金显微组织演变的影响

摘要 增材制造生产的金属材料沿构建方向经历复杂的应力和热旋转。这有可能产生复杂的异质微观结构，这些微观结构可能表现出多种机械性能。关于微观结构异质性的性质和形成机制的研究仍然很少，这限制了我们在增材制造金属材料中进行微观结构设计的能力。在这里，我们对通过选择性激光熔化生产的 CrMnFeCoNi 高熵合金进行了基于电子显微镜的研究。我们专注于对沿构建方向的微观结构演变进行系统研究。我们的结果揭示了显着的微观结构层次，包括纳米晶粒的形成，元素偏析和析出、胞位错结构、变形孪晶和变形诱导相变。我们的研究阐明了不同特征之间的关系，并为增材制造生产的材料的未来结构操作提供指导。