Ellipsoidal equiaxial grain of 7055 aluminium alloy in vacuum centrifugal casting

Abstract

The 7055 aluminium alloy cast tube was prepared by vacuum centrifugal casting technology. The radial and axial microstructure of the alloy was observed by optical microscope and electron probe. The results showed that the as-cast microstructure is uniform and fine equiaxed, and intermetallic compounds are distributed at grain boundaries. In addition, the circumferential grain size and the number of intermetallic compounds were larger than that in the axial direction. The grains are ellipsoidal and equiaxed. This is the result of directional heat conduction, solid solubility migration and redistribution of solute during the solidification process of centrifugal casting. After homogenisation, the grains tend to be spherical equiaxed crystals, which is the result of different degrees of recrystallisation in the circumferential and axial directions.