热处理对高导热Al-11Si合金性能的影响

Effects of Heat Treatment on Properties of High Thermal Conductivity Al-11Si Alloy

对铸造Al-11Si合金进行T6热处理[500℃×2 h固溶+(260~360)℃×(1~8) h时效]试验,研究时效温度与时间对导热性能的影响。结果表明,铸态和热处理态合金的热导率分别为138.5 W/(m·K)和156.6 W/(m·K),T6热处理后Al-11Si合金的热导率提高了14%。相比于时效温度为260℃,320℃时效后合金的电导率在2 h可达到峰值29.05 MS/m,时效温度继续升高至360℃后合金电导率变化不大。T6热处理后α-Al树枝晶长大且更圆整,共晶Si发生球化且分布更均匀,抗拉强度有所下降,伸长率提升明显。α-Al中Si相的析出行为会导致基体晶格常数波动明显。

T6 heat treatment[solution 500 ℃×2 h+(260~360) ℃×(1~8) h] experiments were conducted to investigate the effect of ageing temperature and time on the thermal conductivity of Al-11 Si cast alloy. The results reveal that the thermal conductivity of as-cast and heat-treated Al-11 Si alloy reach 138.5 W/(m·K) and 156.6 W/(m·K), respectively, which is increased by 14% after T6 treatment. Compared to that treated at aging temperature of 260 ℃, the electrical conductivity of the alloy treated at aging temperature of 320 ℃ can reach a peak value of 29.05 MS/m within 2 h, of which the enhancement is slight when temperature is increased up to 360 ℃. After T6 heat treatment, α-Al dendrite grows and becomes more rounded, and the eutectic Si becomes spheroidal and more uniformly distributed, where the tensile strength is decreased, and the elongation is increased significantly. The precipitation behavior of the Si phase in α-Al leads to significant fluctuations of the lattice constant of the matrix.