Abnormal macrosegregation induced by formed porosity during solidification of an Al–Sn alloy

This paper reports in situ investigation of porosity formation and its influence upon the subsequent microstructure development during solidification of an Al–6 wt.% Sn alloy using X-ray imagining and directional solidification and X-ray computed tomography techniques. The growing porosity induces abnormal macrosegregation of Sn above the pores, which is attributed to mass transportation caused by local variations in thermal and solution concentration. The motion of pores due to the abnormal macrosegregation during solidification is also described.