  The effect of ultrasonic melting processing on three-dimensional architecture
of intermetallic phases and pores in two multicomponent cast Al-5.0Cu-0.6Mn-0.5
Fe alloys is characterized using conventional microscopy and synchrotron X-ray
microtomography. The two alloys are found to contain intermetallic phases such
as Al15(FeMn)3Cu2, Al7Cu2Fe, Al3(FeMn), Al6(FeMn), and Al2Cu that have complex
networked morphology in 3D. The application of USP in alloys can obtained
refined and equiaxed microstructures. The grain size of 0.5Fe and 1.0 Fe alloys
is greatly decreased from 16.9 m, 15.8 m without USP to 13.3 m, 12.2 m with
USP, respectively. The results show that USP significantly reduce the volume
fraction, grain size, interconnectivity, and equivalent diameter of the
intermetallic phases in both alloys. The volume fraction of pores in both
alloys is reduced due to the USP degassing effect. The refinement mechanism of
USP induced fragmentation of primary and secondary dendrites via acoustic
bubbles and acoustic streaming flow were discussed.
