2025 Jeong Mg Alloy Multi Heterostructures

Hierarchical multi-heterostructures were synthesized via a subsequent alloying process using Mg90Y10 or Mg90Al10 melt, based on a 3D interconnected FeCr–Mg composite developed through liquid metal dealloying (LMD) in a pure Mg melt. During the first immersion in the LMD process, Ni selectively dissolved from a (Fe80Cr20)50Ni50 precursor into the pure Mg melt, resulting in the formation of a 3D interconnected FeCr–Mg composite. The subsequent alloying with Y or Al in Mg melt induced distinct microstructural evolutions and mechanical properties. Y did not react with the FeCr ligaments but instead incorporated a secondary plate-shaped Mg25Y4 intermetallic phase within the soft Mg region. In contrast, Al addition caused significant microstructural modifications, including the formation of a thick Al-alloyed layer at the solid ligament and an ordered B2 phase. Particularly, the Al alloying reaction within the ligament increased the volume fraction of the solid phase during the subsequent alloying process. Furthermore, the Al-alloyed layer acted as a heterogeneous nucleation site during solidification, leading to the formation of Mg nanograins with a fine lamellar β-Mg17Al12 phase. The 3D interconnected multi-heterostructures, FeCr–(Mg–Mg25Y4) and FeCr–(FeCrAl)–(Mg90Al10), exhibited distinct mechanical properties compared to the unimodal FeCr–Mg composite, demonstrating higher yield strength and ultimate tensile strength. These findings underscore the potential of hierarchical 3D interconnected multi-heterostructures for enhancing the mechanical performance of advanced composite materials through tailored alloying strategies.