Strain induced GdH2 precipitate in Mg-Gd based alloys

► A new rectangle-shape GdH2 precipitate was identified in Mg-Gd based alloys after mechanical polishing or compressive deformation. ► The factors including the H-containing medium, deformation and segregated Gd element are the prerequisites to form GdH2 precipitate. The amount of GdH2 precipitate is mainly influenced by the deformation and the segregated degree of Gd during the solidification. ► A model was introduced to explain the formation of GdH2.