Solution-treated Sr, Zr, Ti and Y quaternary composite microalloyed as-cast high-strength high-plasticity as-cast Al-Si-Mg cast aluminum alloy and preparation method thereof

The invention relates to a solution treated Sr, Zr, Ti and Y quaternary composite microalloyed high-strength and high-plasticity Al-Si-Mg cast aluminum alloy, which is characterized by mainly comprising the following components in percentage by mass: 7.43 to 7.45 percent of aluminum (Al), 0.47 to 0.486 percent of silicon (Si), 0.03 to 0.0385 percent of magnesium (Mg), 0.03 to 0.0385 percent of strontium (Sr), 0.253 to 0.257 percent of zirconium (Zr), 0.0597 to 0.0676 percent of titanium (Ti) and the balance of yttrium (Y). The mass percent of yttrium (Y) is 0.2% (nominal), the balance is aluminum and a small amount of impurity elements, and the sum of all the components is 100%. The preparation process of the alloy comprises casting and solution treatment. The Si phase of the cast aluminum alloy is highly dispersed fine spheres with the size of 2-5 microns, the tensile strength can reach 271.01 MPa, and meanwhile the percentage elongation after fracture is 18.75%. 一种固溶处理的Sr,Zr,Ti,Y四元复合微合金化的高强度高塑性Al-Si-Mg铸造铝合金