Effect of Short T6 Heat Treatment on the Thermal Conductivity and Mechanical Properties of Different Casting Processes Al-Si-Mg-Cu Alloys

Abstract

The thermal conductivity of alloys is gradually becoming appreciated. It is often assumed that heat treatment can improve the thermal conductivity of Al-Si-Mg-Cu alloys, but there has been little relevant research. This paper studies the effects of different casting processes and short T6 heat treatment (ST6) on the thermal conductivity and mechanical properties of Al-Si-Mg-Cu alloys. The results show that a microstructure with fine α-Al crystal grains can be obtained by semi-solid die casting (SSDC), improving the mechanical properties of the Al-Si-Mg-Cu alloy in the as-cast state. After SSDC, the size and aspect ratio of eutectic silicon can be reduced by ST6 treatment, effectively improving the thermal conductivity and mechanical properties of the alloy. Finally, the influence of eutectic silicon on electron transport is analyzed in detail. With the SSDC + ST6 processing technology, Al-Si-Mg-Cu alloys with excellent thermal conductivity and mechanical properties can be obtained.

Selected Properties of a Zr-Containing AlSi5Cu2Mg Alloy Intended for Cylinder Head Castings

“…Thermal conductivity of the experimental alloys in the over-aged T7 state was probably improved due to the formation of fine, uniformly distributed precipitates, which depleted the matrix of solute [17]. Spheroidization and clustering of eutectic Si particles also played important role in thermal conductivity, whereas more favorable conditions for electron movement (as thermal energy carriers) were created (see Figure 10) [34]. When evaluating the thermal conductivity of experimental alloys in the as-cast state, it was found that the presence of Zr resulted in a 6 to 11% (depending on Zr addition) decrease in thermal conductivity in all variants.…”

“…Thermal conductivity of the experimental alloys in the overaged T7 state was probably improved due to the formation of fine, uniformly distributed precipitates, which depleted the matrix of solute [17]. Spheroidization and clustering of eutectic Si particles also played important role in thermal conductivity, whereas more favorable conditions for electron movement (as thermal energy carriers) were created (see Figure 10) [34]. After T7 heat treatment, dissolution of Cu-and Mg-rich intermetallic phases occurred during solution heat treatment, further creating small, more uniformly dispersed precip itate particles.…”

Machine-Learning-Based Thermal Conductivity Prediction for Additively Manufactured Alloys

“…One crucial thermophysical property for various applications is thermal conductivity (TC). The temperature-sensitive TC values are a critical material parameter for heat transfer applications used in various applications including 5G communication technologies [1], cooling components of a computer [2], propulsion systems such as aircraft and rocket engines [3,4] industrial heat exchangers for power, energy, and processing [5] electronic and semiconductor devices [6]. Depending upon the end-use application, different types of materials with varying TC values are required.…”