Microstructure and Mechanical Properties of as-Cast Al-5.0Cu-0.6Mn-0.6Fe Alloy Produced by Ultrasonic Vibration and Applied Pressure

The combined effect of ultrasonic vibration (UT) and applied pressure (P) on the microstructure and mechanical properties of the as-cast Al-5.0Cu-0.6Mn-0.6Fe alloy was investigated by optical microscope (OM), scanning electron microscope (SEM) coupled with energy dispersive X-ray (EDX), image analysis as well as tensile test. The results show that the P+UT processing has an significant effect on the morphology and size of α-Al, Fe-rich intermetallics, and Al2Cu, which promotes the morphology of α-Al transformation from dendritic to globular structure and significantly reduces the size of α-Fe, Al6(FeMn), and Al2Cu phase. The P+UT processing is helpful to reduce the degree of bimodal structure which usually occurs during squeeze casting. It is also effective to reduce the segregation along the grain boundary. The best tensile properties of as-cast alloy produced by the P+UT are ultimate tensile strength (UTS) 268 MPa, yield strength (YS) 192 MPa, and elongation 17.1%, which are 64%, 59%, and 307% higher than those of the non-treated alloy, respectively.