Corrosion mitigation in a quasicrystal-containing Mg-Li-Zn-Y-Ca alloy via heat treatment-induced solute redistribution and secondary phase network reconstruction

A heat-treatment strategy for corrosion mitigation is demonstrated in a quasicrystal containing Mg-4Li-6Zn-1Y-1Ca (wt.%) alloy through solute redistribution and secondary phase network reconstruction. To our knowledge, this is the first report showing that heat treatment-induced construction of a continuous secondary phase network can improve the corrosion resistance of quasicrystal containing Mg-Li alloys. Unlike conventional strategies that aim to eliminate cathodic phases, the present approach enhances corrosion resistance through the coupled effects of secondary phase continuity and dissolution-induced solute redistribution. During heat treatment, the high-potential icosahedral quasicrystalline phase (I-phase, Mg 3 Zn 6 Y) partially dissolves, releasing Zn and Y. The released Y preferentially partitions into the Ca 2 Mg 6 Zn 3 phase to form (Ca, Y) 2 Mg 6 Zn 3 , while part of the Zn dissolves into the α -Mg matrix, thereby reducing local potential differences and weakening micro-galvanic corrosion, as confirmed by SKPFM and DFT analysis. Meanwhile, the Ca 2 Mg 6 Zn 3 phase evolves from discontinuous rods into a continuous network, which suppresses the nucleation and lateral propagation of filiform corrosion, as observed in situ. Heat treatment also increases the MgO fraction and promotes CaCO 3 -assisted pore sealing in the corrosion products, leading to a denser and more protective surface film. As a result, the corrosion rate decreases by approximately 70% relative to the as-cast alloy. These findings demonstrate that engineering secondary phase continuity and solute redistribution provides an effective strategy for improving the corrosion resistance of Mg-Li-Zn-Y-Ca alloys containing multiple secondary phases.