Abstract:

High-pressure die-cast (HPDC) aluminum alloys are widely used for structural applications owing to their excellent castability and high productivity. However, their mechanical performance is strongly influenced by post-casting heat treatment, particularly solution heat treatment (SHT), due to inherent porosity and the formation of Fe-containing intermetallic phases during solidification. Appropriate selection of SHT conditions is therefore essential for improving the mechanical properties of HPDC aluminum alloys.
In this study, the solution heat treatment behavior of a high-pressure die-cast Al–8Si–0.7Cu–0.25Mg–0.2Mn–0.4Fe alloy was investigated using thermodynamic calculations and experimental validation. Thermodynamic calculations using JMatPro were employed to support alloy design and to examine phase formation and solidification behavior. Plate specimens with a thickness of 4 mm were fabricated via high-pressure die casting, followed by solution heat treatment under various conditions. Mechanical properties were evaluated to examine their dependence on SHT parameters.
Microstructural observations were conducted for representative solution-treated conditions to analyze changes in eutectic Si morphology and Fe-containing intermetallic phases. In addition, electrical conductivity measurements were performed to provide complementary information on microstructural evolution associated with solution treatment.
The results indicate that the mechanical properties of the HPDC alloy exhibit a clear dependence on solution heat treatment conditions, enabling the identification of an optimized SHT window that provides an improved balance between strength and ductility. The observed trends in mechanical behavior are consistent with microstructural features and conductivity responses.
This study provides practical insight into the selection of solution heat treatment conditions for high-pressure die-cast Al–Si–Cu–Mg alloys and contributes to a better understanding of process–microstructure–property relationships in HPDC materials.

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Dr. Shae K. Kim