Influence of wall thickness and Sr modification on the heat treatment capability of high-pressure die castings from alloy AlSi9Cu3Fe

Al high-pressure die casting alloys are extensively used for the production of combustion and electric vehicle parts. However, commonly used alloys are mainly only optimised regarding their castability and mechanical properties. The advancing electrification in the mobility sector is altering the demand for parts and their properties, like increased thermal conductivity in combination with high strength for the production of battery housings. The aim of this work is a in-depth study of the combined influence of wall thickness, T6 heat treatment and Sr addition on the mechanical and physical properties of parts produced from HPDC by alloy AlSi9Cu3Fe. This paper utilises a semi-automatic, quantitative microstructure analysis over the sample thickness combined with mechanical and physical property investigations. The results show that the heat treatment response is dependent on the wall thickness and can be improved by a Sr addition, resulting in improved mechanical and physical properties. Via this method, simultaneous improvements of yield strength up to 49% and thermal conductivity up to 20% are possible.