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MM: Fachverband Metall- und Materialphysik

MM 35: Topical Session Heterogeneous Nucleation I

MM 35.4: Talk

Thursday, March 17, 2011, 12:00–12:15, IFW D

Phase-field simulations of inoculation and subsequent peritectic solidification in Ti-Al-B — •Markus Apel, Janin Eiken, and Ulrike Hecht — Access, RWTH Aachen

In Ti-Al based alloys boride particles can be used as grain refiners. By varying the B content in the melt, the formation temperature of boride particles can be adjusted in a way that they act as heterogenous nucleation sites for either the properitectic β- or the peritectic α-phase. We elucidate the effect of borides on microstructure formation by phase-field simulations coupled to a thermodynamic database. Nucleation and growth of small boride particles are explicitly taken into account on a scale below the numerical phase-field interface thickness by using a semi-analytical growth model. The simulation results show a variety of effects: grain refinement due to heterogeneous nucleation on TiB2-particles, interactions between the growing Ti phases and the borides, as well as a pronounced dependency of the phase transformation rates on the dominant nucleation sites.