等温热处理和超声搅拌对过共晶Al-20Si-4Cu-1Mg-0.3Ti合金微观组织的影响

Effect of Ultrasonic Stirring and Isothermal Heat Treatment on Microstructure of Hypereutectic Al-20Si-4Cu-1Mg-0.3Ti Alloy

在过共晶Al-20Si-4Cu-1Mg合金中,采用Ti细化处理,研究了超声处理及等温热处理对细化处理后合金微观组织的影响。结果表明,经超声处理后,Al-20Si-4Cu-1Mg-0.3Ti合金中初晶硅形貌由粗大的板片状逐渐转变为规则的多边形,平均尺寸为45μm左右;保温温度为590℃时,保温时间为30 min,初生α-Al组织分布均匀,等积圆直径达到最小,为86.3μm,保温时间为60 min,球化效果明显,形状因子达到最大,为0.74;随保温度升高和保温时间的延长,初生硅相逐渐转变为椭圆形,平均尺寸逐渐变大。

The effect of ultrasonic treatment and isothermal heat treatment on microstructure of hypereutectic Al-20Si-4Cu-1Mg alloy with Ti refined treatment were investigated in this study. The result indicated that the morphology of primary Si phase transformed from larger flake to regular polygon after ultrasonic treatment, the average size of primary Si phase reached to about 45μm.There were distributed uniformly of α-Al primary phase after isothermal heat treatment in 590℃ for 30 min, then the average of qual-area-circle diameter reached the minimum, which was 86.3μm. There were spheroidization obviously and the biggest shape factor of α-Al primary phase when isothermal heat treatment time was 60 min, the shape factor was 0.74. When the holding temperature and heat treatment time increased, primary Si phase transformed to ellipse gradually with the average size increased gradually.