Role of Heat Treatment Atmosphere on the Microstructure and Surface Morphology of DLP-Fabricated High-Entropy Alloy Components

AlCrFeNiSi high-entropy alloy (HEA) components were fabricated using digital light processing (DLP) 3D printing, followed by debinding under oxygen-rich and oxygen-deficient atmospheres and sintering at various temperatures. The influence of atmosphere on microstructural evolution, elemental redistribution, and mechanical consolidation was systematically investigated. Oxygen-rich debinding induced oxidation-driven gas formation and surface cracking, whereas oxygen-deficient debinding preserved residual carbon that reduced porosity and enabled earlier densification. The layered microstructure progressively vanished with temperature, and full consolidation was achieved at 1100 °C in oxygen-rich and 1050 °C in oxygen-deficient environments. Correspondingly, both processing conditions yielded similar maximum compressive strengths (~5 MPa), although the oxygen-deficient condition attained this strength at a lower temperature. These findings demonstrate that controlling oxygen exposure during debinding provides an effective pathway to reduce the sintering temperature while maintaining the mechanical performance of DLP-printed AlCrFeNiSi HEA components.