A High‐Throughput Diffusion Couple Strategy for Optimizing the Composition of Fe–14Cr–2Y 2 O 3 ‐Based Oxide Dispersion‐Strengthened Steel With Densely Distributed Oxide Nanoparticles

Oxide dispersion‐strengthened (ODS) alloys have been widely studied due to their excellent high‐temperature creep performance and good resistance to radiation damage. However, the conventional mechanical alloying process is associated with a prolonged preparation cycle, challenges in composition control, and limited reproducibility, posing significant obstacles to the compositional design of ODS alloys. Here, we propose a new strategy for effectively screening the composition, microstructure, and properties of Fe–14Cr–2Y 2 O 3 ‐based ODS alloys via a diffusion couple technique. A continuous Ti–Al composition gradient is established within a single diffusion couple, enabling simultaneous evaluation of multiple compositions under identical processing conditions. The inter‐diffusivity along the diffusion path is determined for alloying elements with corresponding uncertainty quantification. A Ti/(Ti + Al) ratio of 0.7 is identified as optimal, yielding a high nanoparticle number density of 7.5 × 10 22 m −3 and an average particle size of ~6 nm—performance metrics that significantly outperform those achieved at other ratios. Correspondingly, the Vickers hardness reaches a peak value of 315.8 HV at Ti/(Ti + Al) ≈0.77, attributed to the synergistic effects of dispersion strengthening and solid solution strengthening. This study establishes a rational, composition‐driven strategy for the high‐throughput design of ODS alloys tailored for nuclear applications, demonstrating that the diffusion couple technique can achieve rapid correlation and efficient screening of composition–microstructure–property relationships.