Chemical Short-Range Ordering in Nanoprecipitates Modulates Planar Faults to Enhance Mechanical Properties

Nanoprecipitates strengthen metallic materials by impeding dislocation motion, but they often compromise ductility. This study introduces a novel strategy to address this challenge by incorporating atomic-scale chemical heterogeneity within nanoprecipitates. For the first time, pronounced short-range ordering (SRO) within L12-ordered precipitates of the Co40Ni30Cr20Al5Ti4Ta1 multi-principal element alloy is observed and confirmed, with its formation mechanism elucidated via density functional theory. Experimental and computational results show that the unique atomic configuration reshapes the energy landscape of planar defects, enhancing the strength and work-hardening capacity. The SRO structure elevates the critical shear stress for dislocation-mediated precipitate shearing while reducing the formation energy of superlattice intrinsic stacking faults, thereby promoting nucleation site formation. This work pioneers a method for modulating atomic-scale heterogeneity within ordered structures, advancing high-performance material design.