Laser powder bed fusion of Al-Doped CoCrNi Medium Entropy Alloy: Microstructural mechanisms imparting high strength-ductility synergy

ZT Zhang and J Tu and XQ Zhang and YK Qiu and YB Du and YX Liang, MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, 927, 148002 (2025).

DOI: 10.1016/j.msea.2025.148002

The Al8(CoCrNi)92 medium entropy alloy (MEA) was successfully fabricated using the laser powder bed fusion (LPBF) technique. Process optimization through orthogonal experiments identified the optimal parameters- scanning distance of 100 mu m, laser power of 180 W, and scanning speed of 500 mm/s-resulting in a high relative density of 99.28 %. The as- printed alloy exhibited a hierarchical heterogeneous microstructure comprising coarse and fine grains, cellular substructures, and nanoscale L12 precipitates. These features synergistically enhanced mechanical properties, yielding a tensile strength of 872 MPa, a yield strength of 568 MPa, and a fracture elongation of 24.6 %. Microstructural characterization and molecular dynamics simulations revealed deformation mechanisms are dominated by dislocation slip, stacking faults, and Lomer-Cottrell locks. This work highlights the potential of LPBF and compositional tailoring to design high-performance structural materials, offering new insights into achieving an optimal balance of strength and ductility through hierarchical heterogeneous structures.

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