Additively-manufactured high-entropy Cantor alloy: Multiscale microstructures and deformation mechanisms

Additive manufacturing (or 3D printing) is revolutionizing product development and manufacturing by enabling rapid prototyping, reducing lead times and costs, and facilitating complex geometries with minimal waste. High-entropy alloys manufactured through this process exhibit intricate multiscale microstructures that significantly influence their mechanical properties. By utilizing in-situ electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM), this study reveals the governing role of the initial hierarchical microstructure of a laser-beam powder bed fusion (PBF-LB) fabricated FeCoNiCrMn alloy on the sequential activation of deformation mechanisms in real-time. The initial high-density dislocation cells and nano-oxides provide a high yield strength of ∼530 MPa. The subsequent continuous deformation pathway, captured via in-situ observations, begins with single-plane slip, which evolves into multiple slip systems as strain increases. Grains oriented along then undergo significant rotations to accommodate plasticity, while twinning becomes prominent at higher strains near the ultimate tensile strength. This synergistic interplay between dislocation slip, grain rotation, and the formation of intricate multiscale networks (nanotwins, stacking faults, Lomer-Cottrell dislocation locks) produces sustained work hardening. Revealing this multi-stage strengthening pathway provides a new understanding of material performance and establishes a basis for future mechanism-driven design of additively-manufactured alloys. • Multiscale heterostructures form in PBF-LB FeCoNiCrMn high-entropy alloy. • Unique checkerboard structures and dislocation cellular structures are observed. • Tensile deformation involves single to multiple slip, twinning, grain rotation. • oriented grains rotate mainly toward to accommodate plastic strain. • Stacking fault-twin networks and Lomer-Cottrell locks enhance work hardening.