Evaluation of composition region for peritectic coupled growth

Abstract

The composition region for stable coupled peritectic growth is evaluated by means of extending Boettinger's analysis. Our present analysis demonstrates that there exists a critical composition between Cα (composition of primary α at peritectic equilibrium) and Cβ (composition of peritectic β at peritectic equilibrium), i.e. Ccrit, separating the peritectic plateau (between Cα and Cβ) into two regions where coupled and banded growth regimes dominate between Ccrit and Cβ and between Cα and Ccrit, respectively. The calculated critical composition, Ccrit, is consistent with the observation in Ni-Al, Ti-Al and Sn-Cd peritectic systems. Effects of interfacial energies of constituent phases and convection on the separation of these two growth regimes are also discussed.