(華南理工大學 機械與汽車工程學院，廣州 510640)
摘 要: 將壓力場和超聲場復合作用于鋁合金的凝固過程，并對比分析無外場、單一外場(壓力場、超聲場)和復合場的作用效果。采用定量金相分析、掃描電鏡、電子探針等手段研究壓力場、超聲場以及壓力和超聲復合場作用下Al-5.0Cu-1.0Fe合金的顯微組織和顯微硬度。結果表明:分別施加50 MPa壓力場和800 W超聲場均能減少α(Al)二次枝晶間距，細化并分散富鐵相和θ(Al2Cu)相，同時改變富鐵相的形貌，使針狀的Al7Cu2Fe相轉變成漢字狀的富鐵相Al6(CuFe);同時復合場比單一外場能更大程度地細化α(Al)二次枝晶間距、富鐵相和θ(Al2Cu)相;單獨施加壓力50 MPa比單獨施加800 W的超聲更能夠有效減少縮松，但同時施加壓力和超聲時效果最佳;同時施加壓力和超聲場時可獲得最高的α(Al)基體顯微硬度。對復合場的作用效果進行初步探討，這是超聲場的空化效應以及聲流效應和壓力場的壓力效應共同作用的結果。
關鍵字: Al-5.0Cu-1.0Fe合金;超聲場;壓力場;富鐵相;顯微組織;顯微硬度
（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
