Microstructure and properties of AlSi12Fe alloy high pressure die-castings under different vacuum levels

AlSi12Fe alloy die castings were produced by vacuum-assisted high pressure die casting (HPDC) process under different vacuum levels: 275 mbar, 112 mbar, and 72 mbar. The porosity, mechanical properties and thermal conductivity of the castings were investigated. The results show that increasing vacuum level can significantly reduce the average porosity and improve yield strength. The Weibull analysis confirmed that vacuum-assisted HPDC improved the repeatability of the tensile properties. Meanwhile, the thermal conductivity increased with the vacuum level. When the porosity reduced from 0.152% to 0.046%, the thermal conductivity increased from 128.52 W/(m·K) to 133.45 W/(m·K).