Pore behaviour during semi-solid alloy compression: Insights into defect creation under pressure

The pre-existing porosity behaviour of globular semi-solid Al–Cu alloys during uniaxial compression is quantified during time-resolved synchrotron tomography at ∼64% and ∼93% solid. At ∼64% solid, both tortuous and round pores exist before deformation, respectively persisting and closing during compression, while at ∼93% solid, pre-existing tortuous pores open under compressive axial strain. It is demonstrated that pore behaviour reflects the immediate grain neighbourhood where the semi-solid alloy acts as a granular material, and that pore opening results from shear-induced dilation during uniaxial compression.