Microstructure evolution and corrosion resistance improvement of Mg–Gd–Y–Zn–Zr alloys via surface hydrogen treatment

Abstract A surface hydrogen treatment is proposed to improve the corrosion resistance of a long-period stacking ordered (LPSO) phase-enhanced Mg–Gd–Y–Zn–Zr alloy. After hydrogen treatment, the block-like LPSO phases are replaced by novel strip-shaped Gd0.5Y0.5H1.96 aggregates in the surface hydrogenated layer with 260 ± 42 μm thickness. The results of immersion tests in a 3.5 % NaCl solution show that hydrogen treatment improves the corrosion resistance of the alloy. As the LPSO phase decomposes, the Zn enriched in the LPSO phase dissolves into a magnesium matrix, which increases the Volta potential of the surface hydrogenated layer.