Hierarchical heterostructured FeCr–(Mg–Mg2Ni) composite with 3D interconnected and lamellar structures synthesized by liquid metal dealloying

Liquid metal dealloying (LMD) has recently attracted significant attention. Because the LMD process enables the production of three-dimensional (3D) interconnected non-noble metallic materials. In addition, the metallic melt medium is useful for the development of heterostructure (HS) metal–metal composites. However, the solidified liquid metal phase (low melting point metals such as Mg, Bi, Sn, or Cu) has a much lower strength than the developed ligament phase (e.g., Fe, FeCr, Ti, etc.). In this study, the soft Mg phase was strengthened by adding alloying element of Ni. A eutectic composition of Mg–10 at.% Ni melt leads to the formation of fine eutectic structure of (Mg–Mg2Ni) within 3D interconnected morphology. This hierarchical heterostructured composite consisted of FeCr ligament and Mg–Mg2Ni lamellar, and a high yield strength of 280 MPa and a noticeable elongation (1.5%) were achieved. The complex 3D morphology of ligament and lamellar geometrically constraint each other, and it prevents the early fracture of brittle Mg–Mg2Ni lamellar phase. The alloy design for the LMD melt gives insights for hierarchical HS materials with outstanding mechanical properties for structural applications.