Liquidus casting of a wrought aluminum alloy 2618 for thixoforming

Abstract

A wrought aluminium alloy 2618 was cast from its liquidus temperature to obtain a fine structure of equiaxed, nondendritic primary grains. In contrast, the structures obtained from casting the alloy from above its liquidus temperature displayed the usual dendritic grains. The primary grains were characterized by image analysis which showed that the average grain size in two dimensions was ~44 μm and the average circularity factor was ~18, indicating that the grains were both fine and globular. Some particles were also viewed in three dimensions and this showed mostly round and smooth surfaces although some protrusions could be seen to emerge on some particles. The misorientation angles betwe..