Simultaneously improve the strength and ductility of additively manufactured Y2O3/316 L composites via optimizing heat treatment

The effect of heat treatment temperature on the microstructure and mechanical properties of Y₂O₃/316 L composites prepared by laser powder bed fusion was studied. The cellular substructures formed in the as-built samples remained stable when heat-treated at 1000 °C and disappeared as the temperature increased to 1100 °C. Compared with the as-built sample, a larger number of fine particles precipitated in the sample at 1000 °C, and the particles were significantly coarsened at 1100 °C. Under the stress-induced grain boundary migration mechanism, the grains undergo coarsening. The samples heat-treated at 1000 °C had the best combination of strength and ductility compared to the other samples. The high strength of the samples can be attributed to the retention of the cellular substructure and the enhancement of the Orowan strengthening mechanism. The high ductility of the sample is brought about by the formation of the twinned structure. The heat treatment developed in this work for the additive manufacturing of steel matrix composites to tailor its microstructure and mechanical properties for its various applications is critical.