固溶温度对铸造Al-Si合金热导率及力学性能的影响

采用金属型铸造工艺制备高性能导热Al-Si合金,并用单项试验法研究热处理工艺(固溶温度)对合金显微组织、热导率及力学性能的影响。通过光学显微镜(OM)、扫描电镜(SEM)、激光导热分析仪、拉伸试验等手段测试并分析了热处理前后合金显微组织、抗拉强度、伸长率和热导率等性能的变化。结果表明,铸态时合金的热导率为153.1 W/(m·K),随着固溶温度升高,初生α-Al相形状变得规则,共晶Si由不规则的层片状开始断裂和球化,合金的热导率呈先上升后下降的趋势,在540℃时达到最大,为190.8 W/(m·K),较铸态时提高了24.6%,而560℃时急剧降低。抗拉强度由铸态时的188.35MPa提高到540℃时的255.74MPa,伸长率由铸态时的4.5%提升到540℃时的14.41%。

Effects of Solution Temperature on Thermal Conductivity and Mechanical Properties of Cast Al-Si Alloy

The Al-Si alloy with high thermal conductivity was prepared by the metal mold casting,and the effects of heat treatment parameters(solution temperature)on the thermal conductivity and mechanical properties of the alloy were investigated by a single test method through optical microscopy(OM)and scanning electron microscopy(SEM),laser thermal conductivity analyzer,tensile test and other characterization methods to analyze comparatively the microstructure,tensile strength,elongation and thermal conductivity of the alloy before and after heat treatment.The results reveal that thermal conductivity of the alloy reach 153.1 W/(m·K),the shape of the primaryα-Al phase becomes regular with the increase of the solution temperature after solution treatment,and the eutectic silicon begins to break and spheroidize from irregular lamellar.The thermal conductivity of the alloy is increases first and then decreased.At 540℃,the maximum value is 190.8 W/(m·K),which is increased by 24.6%,while it is decreased sharply at 560℃.The tensile strength is increased from 188.35 MPa at the as-cast state to 255.74 MPa at 540℃,and the elongation is increased from 4.5% to 14.41%.