SOLIDIFIED STRUCTURE SIMULATION OF Ti-(45-48)Al ALLOY INGOT WITH CONSIDERATION OF PERITECTIC REACTION

Solidified structure modeling of Ti-(45-48)A1 alloy (atomic fraction, %) ingot has been carried out by using a new cellular automaton method coupled with macroscopic heat transfer calculation. Cells are divided into primary and peritectic ones. Different cells take the different solidification paths. By the new method, the formation of peritectic phases can be shown graphically throughout solidification. The formation of shrinkage cavity at the top of the ingot is included in the calculation. A special-moving-allocation technique is designed to minimize the computation costs and memory size associated with a large number of cells. The potentiality of the present model is demonstrated by comparing the simulated results with the experimental one. The influences of convection and initial alloy composition on the grain structures are studied and the mechanisms producing these results are discussed. The simulated results indicate that the size of equiaxed zone increases with increasing the convection coefficient and alloy composition. And the number of peritectic phases decreases as the alloy composition decreases.