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

Abstract

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)xNi100−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.