Exceptional abrasive wear resistance of immiscible Mg-Fe₈₀Cr₂₀ composites with 3D interconnected structure developed by liquid metal dealloying

Three-dimensional (3D) interconnected heterogeneous composites prepared through liquid metal dealloying (LMD) have been studied owing to their unique structural features and interesting deformation behavior beyond the strength-ductility trade-off. In this work, we systematically investigated the abrasive wear mechanism of 3D interconnected composites comprising immiscible Mg and Fe₈₀Cr₂₀ as a function of the fraction of hard Fe₈₀Cr₂₀ phase. (Fe₈₀Cr₂₀)_xNi_100−x precursor alloys were used in the LMD process, and the miscible Ni element dissolved in the Mg melt. Subsequently, the self-organization of the solid Fe₈₀Cr₂₀ led to a 3D interconnected composite containing penetrated Mg structures. The volume fraction of Mg phase and microstructural features of the composites were highly influenced by the initial Ni concentration. Although the composites had a brittle interface because of the immiscibility of Mg and Fe₈₀Cr₂₀, the 3D interconnected structures exhibited exceptional abrasive wear resistance beyond expectations. Highly deformed structures were observed on worn surfaces, and wear mechanisms differed from those of bulk Mg and Fe₈₀Cr₂₀ materials. During the wear test, the area fraction of Fe₈₀Cr₂₀ phase on the worn surface increased significantly, and the presence of nanograined Fe₈₀Cr₂₀ layers with a high dislocation density effectively protected the underlying soft Mg phase. In particular, the Mg-based tribofilm acted as a lubricant in the 3D interconnected structure. These findings related to the improvement of wear resistance through structural design could serve as guidelines for various applications of heterogeneous 3D architecture materials.