Effect of Different-Source Ultrasonic Treatment on Intergranular Phase and Mechanical Properties of Large-Scale AlCu Ingots

Abstract

Large-scale AlCu ingots (830 mm in diameter and 6000 mm in length) were cast under different ultrasonic treatment conditions (with a single sonotrode and with four sonotrodes), in a cylindrical mold with a hot top and direct-chill casting system. The microstructure and mechanical properties of the ingots were compared between the ingot solidified without ultrasonic treatment, with the single sonotrode, and with four sonotrodes. After ultrasonic melt treatment, the α-Al grains of the ingots were refined. Meanwhile, macro-segregation of Cu in the ingots was ameliorated, and the area fractions of coarse Al2Cu eutectic phases were decreased. In particular, the area fraction of the Fe-rich phase in the ingot cast with four sonotrodes was greatly reduced. Due to the refined α-Al grains and the reduction of coarsening intergranular phases, the mechanical properties of the ingot cast under ultrasonic treatment were greatly improved, especially in the ingot cast with four sonotrodes.