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

• An internal hydrogenation was proposed to alter the microstructures of alloy surface. • Gaseous hydrogen charging of Mg–Gd–Y–Zn–Zr alloy was carried out at 482 °C. • The novel strip-shaped REH x aggregates replaced LPSO phases in hydrogenated layers. • The surface hydrogenated layer exhibits improved corrosion resistance. 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 Gd 0.5 Y 0.5 H 1.96 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. [ABSTRACT FROM AUTHOR]