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Nanocrystalline stainless steels exhibit limited thermal stability due to their high-volume fraction of grain boundaries, making them susceptible to grain growth at elevated temperatures. Enhancing thermal stability is therefore essential to broaden their potential structural applications. In this study, we present recent investigations from our laboratory on the microstructural stability, phase transformations, and hardness of nanocrystalline 304L stainless steels synthesized via high-energy mechanical alloying with solute and nanoscale ceramic additions. The effect of solute element and ceramic particle additions, as well as sintering temperature, on structural and microstructural evolution were systematically investigated using X-ray diffraction (XRD), focused ion beam (FIB) microscopy, and transmission electron microscopy (TEM). The mechanical behavior was evaluated using hardness measurements and correlated with the corresponding microstructural features. The results demonstrate that high-energy mechanical alloying results in a deformation-induced martensitic transformation, followed by a reverse transformation during sintering. Despite substantial grain growth in nanocrystalline 304L stainless steel at elevated sintering temperatures, the addition of solute elements and ceramic particles significantly improves grain size stability and hardness. This research was supported by TENMAK under Grant No. 2071, and the authors gratefully acknowledge this support.
Keywords: Nanocrystalline 304L stainless steel; Solute segregation; Ceramic particle additions; Grain growth; Hardness© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.