| With the popularization of 5G communication technology and the acceleration of data transmission rate,the heat dissipation capacity of base stations is challenged.Al-Si alloy is the "first choice" material of base station radiator,and its thermal conductivity and mechanical properties can hardly be improved at the same time.Therefore,how to make the alloy have good mechanical properties and excellent thermal conductivity at the same time to meet the application needs is the key of research.At present,the methods of alloying,heat treatment and modification mainly focus on the improvement of mechanical properties,while the research on thermal conductivity is relatively less.As a general rule,the thermal conductivity of the alloy depends on the distribution of alloy elements,the morphology of the second phase and the types of precipitates.The mechanical properties and thermal conductivity can be effectively balanced by adding appropriate types of alloying elements.Combined with heat treatment,the morphology of the second phase and the types of precipitated phases are changed,so that the thermal conductivity and mechanical properties of the alloy are further improved.In conclusion,discussing the effects of alloying and heat treatment on the microstructure and properties of Al-Si alloy has important practical application value and research significance for optimizing the manufacturing process and developing alloys with good comprehensive properties.In this paper,based on Al-Si alloy,the alloy composition was optimized by orthogonal test,and the influence of different contents of Si,Mg and Cu on the microstructure and properties of the alloy was discussed.Through the solution heat treatment of the alloy in different systems,the influence rule and mechanism of solution heat treatment parameters on the microstructure and properties of Al-8Si alloy were studied.Then,the influence rule and mechanism of different aging heat treatment systems on the microstructure and comprehensive properties of the alloy were studied.Finally,the optimal heat treatment process was optimized by orthogonal test.The main results are as follows:(1)The alloy with the optimal composition of Al-8Si-0.6Mg-0.1Cu was optimized by orthogonal test.The influence of Si,Mg and Cu on the strength of the alloy is Si>Mg>Cu,and the influence on the thermal conductivity of the alloy is Mg>Cu>Si.(2)The Al-8Si alloy was subjected to solution heat treatment.The results show that the thermal conductivity of Al-8Si alloy reaches the highest value of 191.2 W/(m·K)when the solution time is 0.5h,and the eutectic silicon size is relatively small and the aspect ratio is the lowest.When the solution time is prolonged,the size and aspect ratio of eutectic silicon increase,and the thermal conductivity of the alloy decreases.(3)The Al-8Si-0.6Mg-0.1Cu was treated by solution heat treatment.The results show that when the solution temperature increases,the thermal conductivity of the alloy decreases,but its HV gradually increases.After solid solution at 535? for 4 hours,Mg and Cu were completely solid solution,and the hardness reached the peak value of 71.7 HV.(4)The Al-8Si-0.6Mg-0.1Cu was aged by single stage and double stage respectively.The results show that the strength and thermal conductivity of Al-8Si-0.6Mg-0.1Cu alloy are improved by the combination of pre-aging and secondary aging with slight over-aging.(5)By optimizing the heat treatment process of the alloy,the best heat treatment process is obtained.Under this heat treatment process,the tensile strength of Al-8Si-0.6Mg-0.1Cu alloy is 340.8 MPa and the thermal conductivity is 185.6 W/(m·K).According to the experimental results,the temperature parameters of secondary aging have the greatest influence on the strength of the alloy,followed by the sum of temperature parameters of preaging and the holding time under secondary aging,and the influence of solution time is relatively small.For thermal conductivity,the temperature parameter of secondary aging has the greatest effect,followed by the holding time of secondary aging process and the temperature parameter of pre-aging process,and the influence of solution time is relatively small. |
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