Effects of Nd and Cu on Microstructure and Mechanical Properties of Hypereutectic Alâ€20Si Alloy

Abstract

In this paper, the modification of Nd to hypereutectic Al–20Si alloy was studied, and the effects of Cu on the microstructures and mechanical properties of the modified Alâ€20Si alloy were investigated. The results showed that the primary Si transformed from irregular morphology to fine polyhedral morphology, and the morphology of eutectic Si transformed from acicular/ lamellar to shortâ€rod and point like after modification. Compared with Alâ€20Si alloy, the tensile strength of Alâ€20Siâ€0.3Nd increased by 22.8%, and the elongation increased by 127.8%. The strengthening phase CuAl2 appeared in the Cuâ€containing Alâ€20Siâ€0.3Nd alloy; as a result, the mechanical properties of Alâ€20Siâ€0.3Ndâ€Cu alloy were improved. Compared with Alâ€20Si alloy, the tensile strength of Alâ€20Siâ€0.3Ndâ€2.0Cu alloy increases by 39.5%, and the elongation doesn’t decrease.