Prediction of the maximal recalescence temperature upon rapid solidification of bulk undercooled Cu₇₀Ni₃₀ alloy

Applying melt-fluxing, how to predict the maximal recalescence temperature T_R upon rapid solidification of bulk undercooled Cu₇₀Ni₃₀ alloy has been investigated. Reproducible experimental results show that T_R decreases with the increase of the initial melting undercooling ΔT, and moreover, its value is much lower than that predicted by Level rule and Scheil equation, let alone the equilibrium liquidus temperature. Quantitative thermodynamic calculation, in combination with an analysis of solute distribution, demonstrates that, T_R is affected by the difference of Gibbs free energy between the residual liquid and solid after recalescence. Subjected to sufficiently high ΔT, T_R should be nearly equal to the thermodynamic T₀ point corresponding to the concentration of the residual melt after recalescence.