Influences of microstructure and orientation on fracture toughness of intermetallic phase Al₂Cu-based alloy under directional solidification

The influences of microstructures and orientations on fracture toughness of intermetallic phase Al₂Cu-based alloys during different directionally solidified rates were investigated. With solidified rates increasing, the patterns of Al₂Cu phase dendrite turned from faceted V-shaped morphology to elongated plate-shaped morphology and discontinuous complex morphology in longitudinal section. Moreover, the deviation angle between the growth direction of Al₂Cu dendrite and the heat flow direction was increasing. Because of fine grain toughening and crack propagation path deflected by orientation, the fracture toughness of Al₂Cu-based alloy was improved. The experimental results showed that improving the brittleness could be well achieved under higher directionally solidified rate.