(华南理工大学 机械与汽车工程学院，广州 510640)
摘 要: 将压力场和超声场复合作用于铝合金的凝固过程，并对比分析无外场、单一外场(压力场、超声场)和复合场的作用效果。采用定量金相分析、扫描电镜、电子探针等手段研究压力场、超声场以及压力和超声复合场作用下Al-5.0Cu-1.0Fe合金的显微组织和显微硬度。结果表明:分别施加50 MPa压力场和800 W超声场均能减少α(Al)二次枝晶间距，细化并分散富铁相和θ(Al2Cu)相，同时改变富铁相的形貌，使针状的Al7Cu2Fe相转变成汉字状的富铁相Al6(CuFe);同时复合场比单一外场能更大程度地细化α(Al)二次枝晶间距、富铁相和θ(Al2Cu)相;单独施加压力50 MPa比单独施加800 W的超声更能够有效减少缩松，但同时施加压力和超声时效果最佳;同时施加压力和超声场时可获得最高的α(Al)基体显微硬度。对复合场的作用效果进行初步探讨，这是超声场的空化效应以及声流效应和压力场的压力效应共同作用的结果。
关键字: Al-5.0Cu-1.0Fe合金;超声场;压力场;富铁相;显微组织;显微硬度
（School of Mechanical and Automotive Engineering, South China University of Technology,
Guangzhou 510640, China）
Abstract:Compound field was firstly used to influence the solidification of Al alloy, and the effect of different field on the microstructure and mechanical properties was investigated. The microstructure and micro-hardness of Al-5.0Cu-1.0Fe alloy treated by compound field (combination of 50 MPa pressure field and 800 W ultrasonic field) were studied by image analysis, scanning electron microscopy and electron probe micro-analysis. The results show that both 50 MPa pressure field and ultrasonic field decrease the second dendritic arm spacing, thin and spread the second intermetallics. Meanwhile, large amounts of iron-rich phases transform from acicular shape to Chinese script morphology. Compared with the single field, the microstructure of the alloy treated by compound field is refined and modified more obviously. The casting defects, such as porosity, are reduced more efficiently when 50 MPa pressure field is applied, and the alloy applied compound field has the highest micro-hardness with the smallest volume percentage of porosity. The mechanism of compound field was also preliminarily discussed, which results from ultrasonically-induced cavitation and acoustic streaming effect and pressurely-induced pressure effect.
Key words: Al-5.0Cu-1.0Fe alloy; ultrasonic field; pressure field; iron-rich phases; microstructure; micro-hardness
