Non-equilibrium transformation path for bulk undercooled hypereutectic Fe-B alloy

Assuming phenomenological thermal flow balance and solute conservation, the non-equilibrium transformation path has been studied for recalescence of bulk undercooled hypereutectic Fe-B alloy. Taking advantage of the defined stoichiometry for primarily formed intermetallic Fe₂B, a convenient and accurate tracking of the average liquid concentration during recalescence can be performed. Applying thermodynamic calculations for liquid/solid Gibbs energy difference, the predictions of the post-recalescence temperature T_R and the as-formed solid fraction in recalescence are shown to be in good agreement with the experimental results. On this basis, a transformation path accompanied by the evolution of temperature and concentration in the residual liquid has been constructed. This clearly shows a transition from non-equilibrium to near-equilibrium process upon recalescence.