Direct observation of the segregation driven by bubble evolution and liquid phase separation in Al–10 wt.% Bi immiscible alloy

The effects of the growth behaviors of bubbles and minor droplets on the segregation in solidifying Al-10 wt.% Bi immiscible alloy were investigated by synchrotron radiography. The Bi atoms were effectively trapped at the surface of bubbles, favorable to the bubble growth. With cladding Bi layer, the stochastic growth of bubbles remains, but the scaled size distribution follows neither Gaussian nor Lifshitz-Slyozov-Wagner (LSW) controlled distributions. The variation in Bi droplet number over time obeys a logistic curve. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.