High thermal conductivity Al-Si-Mg-Cu alloys were prepared by water-cooled copper mold.The microstructure

morphology and distribution of precipitated phases

hardness and thermal conductivity of the alloy were analyzed after solution and aging treatment.The evolution of microstructure and properties of the alloy during solution and aging treatment were analyzed.The results reveal that the alloy is mainly composed of primaryα-Al

eutectic Si phase

Mg

2

Si phase and iron-rich phases under as-cast state.After solution and aging treatment

the alloy phase composition presents the absence of change

however

morphology and distribution of precipitates change obviously.The eutectic Si phase is obviously spheroidized during the solution process with more uniform distribution after aging treatment

while Mg

2

Si and iron-rich phases have the smaller size and more uniform distribution after aging treatment.The solution and aging treatment have impact on morphology

size and distribution of the precipitated phase

which would reduce the probability of scattering during free electron transport

and build more channels for free electron transport in order to achieve the simultaneous optimization of the mechanical properties and thermal conductivity.Finally

the micro-hardness and the thermal conductivity of the alloy prepared reach 122.92 HV and 162.73 W/（m·K）

respectively.