Growth Behaviors of Bubbles and Intermetallic Compounds in Solidifying Al-5 wt.% Mn Alloy

The growth behaviors of hydrogen bubbles and intermetallic compounds (IMCs) during solidification of an Al-5 wt.% Mn alloy was investigated by synchrotron radiography. Results show that bubble collapse can increase hydrogen concentration in nearby Al melt, thus facilitating the formation and growth of new bubbles. Under the interference of Al6Mn IMCs, the growth method of an individual bubble is changed from a Gaussian distribution to a linear model. Al6Mn crystal growth can be divided into three stages: first an isotropic spherical crystal appears, then it evolves into primary branches, and eventually forms an irregular octahedron.