稀土La变质Al-12.35Si合金的组织及性能

Near-eutectic Al-12.35Si alloy containing various alloying elements was modified by the rare earth La element through adding the Al-La master alloy, and effects of the addition amount (0.1%~0.8%) of La on the microstructure and mechanical properties of Al-Si alloy were investigated. The results reveal that the proper addition amount of La can reduce the size of long needle-like eutectic silicon, refine the second phase, and reduce the primary α-Al secondary dendrite arm spacing (SDAP). Excessive La can cause excessive deterioration, resulting in coarsening of the alloy structure. When the La content is 0.2%, the Al-Si alloy has the desirable modified solidification structure and mechanical properties, where the tensile strength of alloy is increased from 168 MPa to 188 MPa, and the elongation is increased from 0.44% to 0.53%. With the increase of La content, both the strength and plasticity of the alloy are declined.