Low-cost low-density high-modulus magnesium alloy and preparation method thereof

The invention provides a low-cost, low-density and high-modulus magnesium alloy and a preparation method thereof. The magnesium alloy comprises the following elements in percentage by mass: 2.5 to 5 weight percent of Al, 2 to 4 weight percent of Ca, 0.2 to 0.6 weight percent of Mn, 3.5 to 6.5 weight percent of SiC particles and the balance of Mg and inevitable impurities. The preparation method comprises the following steps: mechanically stirring a melt, quickly adding SiC particles after the melt forms a stable vortex, continuously stirring after the SiC particles are added, so that the SiC particles are uniformly distributed in the melt, carrying out secondary dispersion on the SiC particles in the melt by adopting ultrasonic treatment, and obtaining a magnesium alloy cast ingot by adopting a mode of air cooling and then water cooling, and after homogenization treatment, three-time upsetting and three-time drawing are conducted, and extrusion deformation is conducted. According to the method, the elasticity