Microstructure and Thermal Conductivity of Al-10Si-x Mg Alloys Prepared by Spray Ejection
Effects of Mg content on microstructure,thermal conductivity and hardness of as-cast and T6 heat-treated Al-10Si-x Mg alloys prepared by spray ejection were investigated.The results indicate that Mg inhibits the formation of dendrites and promotes spheroidization for α-Al grains,and reduces the segregation of eutectic Si,distinctly improving homogeneity of eutectic Si phase in T6 heat-treated alloys.The optimization of eutectic Si can reduce electron scatter-ing and effect of Mg solution on electron scattering,leading to a high electron mobility of 399.2 cm2/(V∙s)for the T6 alloys with Mg content of 0.4%,and thermal conductivity is 172.4 W/(m∙K),which is decreased by 5.5%compared to that of Al-10Si alloy.Meanwhile,the micro-hardness is significantly enhanced due to strengthening of eutectic Si and Mg2Si phase,and a large Vickers hardness of 1.13 GPa is achieved for T6-treated specimens with Mg content of 0.4%,which is increased by 126%compared to that of Al-10Si alloy.The results reveal that the thermal conduction and mechanical properties of Al-10Si-x Mg alloys can be synergistically regulated by tailoring Mg content,resulting in excellent comprehensive performance.
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