LAUSR

Abstract Different dendritic grain morphology of an Al-Cu alloy was obtained by adjusting the casting parameters. Compared to the equiaxed dendritic grains, the tortuous dendritic grains led to increased tensile elongation (from 10.4% to 16.8%) and work of fracture (from 11.2 J/mm2 to 17.2 J/mm2) by more than 50%, respectively. Meanwhile, the high tensile strength (∼540 MPa) and grain size (∼80 μm) were unchanged. The intergranular fracture crack zigzagged along tortuous grain boundaries, reducing the stress concentration at the crack tip and increasing the propagation resistance and path, leading to increased toughness and elongation. The zigzag morphology of grain boundaries was attributed to tortuous dendritic grains.