The invention discloses high-strength
magnesium-aluminum-
manganese-
strontium alloy. The
alloy is prepared from the following ingredients in percentage by
mass: 1.0-5.0% of Al, 0.1-1.5% of Mn, 0.1-5% of Sr, not higher than 0.15% of unavoidable impurities and the balance of
magnesium. The invention further discloses a method for preparing the high-strength
magnesium-aluminum-
manganese-
strontium alloy. The method comprises the following steps of: (1) selecting raw materials according to the formula, and
smelting in a
vacuum induction furnace so as to form alloy; (2) removing an
oxide layer from the surface of the alloy obtained in the step (1); (3) carrying out annealing on the alloy obtained in the step (2); and (4) carrying out
extrusion processing on the alloy obtained in the step (3). According to the alloy disclosed by the invention, due to the
strontium element, the degree of super-cooling of the alloy is increased, the
crystal grains are refined, strontium is enriched at a growth interface during solidification, and the growth rate of the
crystal grains is reduced; and furthermore, an Al4Sr phase is formed by strontium and aluminum, so that the recrystallization growth of the
crystal grains can be inhibited. The alloy disclosed by the invention is low in cost, and the preparation method is simple.