The invention provides a preparation method for a rear-earth
magnesium alloy. The preparation method comprises the following steps of:
casting a
magnesium melt, extruding and forming after
solution treatment, then carrying out cold-rolling and
ageing treatment to obtain the rear-earth
magnesium alloy, wherein the rear-earth
magnesium alloy comprises Mg, Nd, Gd, Y, Zn and Zr. Compared with the prior art, cold-rolling and
ageing treatment is carried out after carrying out
solution treatment, extruding and forming, so that a great number of beta phases and LPSO phases exist on a
crystal boundary, the
crystal boundary is pinned to prevent crystalline grains from growing in a transformation process, crystalline grains in the
alloy are refined, and therefore, yield strength of the rear-earth
magnesium alloy is improved; the rear-earth
magnesium alloy has the LPSO phases with 14H structures, and is regularly distributed along extruding direction; stability of the boundary improves strength and
toughness of the rear-earth magnesium alloy; moreover, high-density
dislocation is introduced in cold-rolling, and
nucleation of beta' phases in an
ageing process is promoted, so that ageing
hardening effect of the alloy is improved; meanwhile, the beta' phases can be more refined by the cold-rolling.