In-situ observations of dendritic fragmentation during directional solidification of Sn-10wt.% Bi alloy

Abstract

The stray crystals seriously affect the properties of metals which fabricated by directional solidification (DS). In order to observe the formation of the stray crystals, the growth behavior of Sn-10wt.%Bi alloy was observed by synchrotron X-ray imaging technique using self-developed directional solidification (DS) apparatus. The experimental results show that Sn-10wt.%Bi alloy is oriented with the form of dendrites to grow into the liquid phase during the DS process, and dendrites are arranged neatly to form columnar crystal microstructures. It is also found that parts of the dendrite arms begin to crack. These cracked dendrites drift upward to grow up in front of the solid-liquid interface and form stray crystals.