In this study, the heterogeneous anisotropic microstructure and mechanical properties of additively manufactured (CoCrFeMnNi)₉₉C₁ high-entropy alloy (HEA) are comprehensively investigated using experimental and theoretical analyses. For the present alloys, the selective laser melting (SLM) process produced orthogonally anisotropic microstructure with not only strong macroscopic morphological but also sharp microscopic crystallographic textures. Moreover, due to the complex thermal gradient and history in the melt pools, the columnar grains were heterogeneously evolved along the building direction with alternatively arranged layers of fine and coarse grains parallel to the laser scanning direction. This unique morphological texture played a dominant factor for the big difference in tensile properties between different loading directions in the early stage of deformation. In particular, the alternatively arrangement of fine and coarse grains could generate high hetero-deformation induced (HDI) hardening along the scanning direction in the as-built samples by profuse evolution of geometrically necessary dislocation at the boundaries of each layer. On the other hand, upon the last stage of plastic deformation, the crystallographic texture played a crucial role in directional flow behavior by modulating twinning activity. The combined contribution of the various anisotropic microstructural factors to the tensile properties of the SLM-processed HEAs was clarified both qualitatively and quantitatively. This work will shed light on effective utilization of both heterogeneity and anisotropy of the structural parts for customized performance via expanding multi-scale freedom of design in additive manufacturing.

在这项研究中，增材制造的（CoCrFeMnNi）₉₉ C ₁的异相各向异性组织和力学性能使用实验和理论分析全面研究了高熵合金（HEA）。对于本发明的合金，选择性激光熔融（SLM）工艺产生了正交各向异性的微观结构，其不仅具有强的宏观形态，而且具有清晰的微观晶体学织构。此外，由于复杂的热梯度和熔池中的历史，柱状晶粒沿着构造方向异质地演化，交替排列的细晶粒和粗晶粒层平行于激光扫描方向。这种独特的形态织构是变形初期不同加载方向之间拉伸性能差异较大的主导因素。尤其是，细晶粒和粗晶粒的交替排列可通过在每一层边界上大量发生几何上必要的位错演变，从而在生成的样品中沿扫描方向产生高的异质形变诱导（HDI）硬化。另一方面，在塑性变形的最后阶段，晶体结构通过调节孪晶活性在定向流动行为中起着至关重要的作用。定性和定量地阐明了各种各向异性的微观结构因素对SLM处理的HEA的拉伸性能的综合贡献。这项工作将通过扩展增材制造中设计的多尺度自由度，有效地利用结构零件的异质性和各向异性来实现定制性能。