Effect of Homogenization Temperature on Microstructure and Conductivity of Al-Mg-Si-Ce Alloy

Abstract

Microstructure evolution of Al-0.2wt.%Mg-0.36wt.%Si-0.3wt.%Ce alloy at three different homogenization temperatures for 6 h was observed by optical microscopy, scanning electron microscopy, and x-ray diffraction. Conductivity and tensile properties of the alloy were tested. Results indicate that homogenization temperature has little effect on the macro-segregation and grain size of the as-cast Al-Mg-Si-Ce alloy; however, it has a significant effect on the conductivity. The conductivity is first improved to a maximum value of about 57.3% IACS with homogenization temperature increasing to 560 °C (2.7% higher than that of the as-cast sample), and then decreased when the temperature continuously increasing. The main contributor is considered to be vacancy concentration, which is directly related to the lattice distortion, thus affects the conductivity. The studied homogenization temperatures almost make no difference among the tensile properties of the alloy. The best homogenization temperature for Al-0.2wt.%Mg-0.36wt.%Si-0.3wt.%Ce alloy is 560 °C with the highest conductivity and no decrement of strength.