A large-scale cylindrical 2219 Al alloy ingot (1 250 mm in diameter and 3 300 mm in length) is manufactured using a special DC casting facility. Macrosegregation of major element (Cu) at different casting stages is determined on three cross-sections of as-cast ingot. Meanwhile, the evolution of temperature filed in the sump is simulated at different casting stages. Further, the relationships, between macrosegregation, temperature field, and grain structures, are investigated. These work provide some insights in the macrosegregation formation during large-scale casting or solidification, further promoting to manufacture the large-scale metallic ingots for potential application.

The work described in this paper dealt with the effect of ultrasonic vibration on the solidification of 7050 aluminum alloy. Two experiments were carried out through introducing ultrasound into the semi-continuous direct-chill (DC) casting of aluminum alloy and into alloy solidifying in a crucible, respectively. Results show that ultrasonic vibration can refine grains in the whole cross-section of a billet in the first experiment and is able to increase the cooling rate within the temperature range from 625 °C to 590 °C in the other one. The mechanism of particle resonance caused by ultrasonic vibration was illustrated on the basis of theoretical analysis of the kinetics and energy conversion during the solidification. It is demonstrated that the kinetic energy of resonant particles are mainly from the latent heat energy of solidification, which can shorten the cooling time, inhibit the crystal growth and then lead to the grain refinement.

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