Correlation Among Microstructure, Mechanical Properties, and Thermal Stability of a Novel HPDC Al–12Si Alloy with Minor Sc

Abstract

The microstructure, mechanical properties, and thermal stability of high-pressure die casting (HPDC) Al–12Si–Sc alloy with 0.1 wt% Sc addition are investigated. Compared with the commercial A380 alloy, the alloy shows a significant refinement of α-Al and eutectic Si microstructure. Meanwhile, β-Fe with irregular morphology shows a smaller size and lower volume fraction in Al–12Si–Sc alloy. Upon as-cast state, the elongation of the alloy is improved to 6.7% with an ultimate tensile strength of 332 MPa, which is a better combination of ductility and strength in the literature. After thermal exposure at 200 °C for 200 h, it retains tensile strength of 277 MPa and holds the microhardness up to 90 HV even exposure for 1000 h. These excellent properties may widen the application of HPDC Al–Si alloy for the cylinder block and cylinder head.