2019 Volume 105 Issue 7 Pages 709-715
In-situ X-ray transmission imaging experiments were performed to the simulated molten zinc baths of CGL in order to clarify the nucleation and growth behavior of Fe2Al5 solid intermetallic compound called “top dross”. Zn alloy samples containing a small amount of Fe and Al were melted in a high vacuum atmosphere and cooled by various rates. The in-situ X-ray transmission observations were performed during the cooling process. The nucleation and growth behavior of Fe2Al5 particles were observed directly. The nucleation behavior is strongly affected by cooing rate, as cooling rate gets faster, the average particle size gets smaller and the number of particles increases. The total volume of crystallized particles is not changed by cooling rate. It is suggested that we have a possibility to control their size or number of dross particles by controlling bath temperature. Their nucleation behavior also suggested that they need a certain amount of Al, Fe supersaturation or supercooling in order to nucleate new dross particles in the bath. The growth speed of the particles in the molten zinc was also analyzed by image analysis. It is suggested that the growth behavior of Fe2Al5 particles is restricted by the diffusion of Fe, Al components. In-situ X-ray imaging method can be a promising technique to understand the nucleation or growth behavior of dross particles generated in CGL baths.
