Abstract
(a) Phase diagram in Fahrmann et al. (1997) at 927 °C. (b) Phase diagram from Thermocalc at 775 °C. The curvature of the free energy surface (for the γ phase) is overestimated by ThermoCalc and hence a critical comparison between experimentally observed coarsening rate and predictions of phase field model is difficult. [Display omitted]
•Coarsening behaviour in Ni-Al-Mo alloys compared with 3D simulations.•CALPHAD’s estimate of curvature of free energy curves not accurate.•Accurate thermodynamic data needed to make better predictions of coarsening behaviour.
In this paper, we attempt a critical and quantitative comparison between our phase field model and experimental results on coarsening in ternary two phase alloys. For experimental results, we have chosen a specific Ni-Al-Mo alloy [Ni-7.7% Al-7.9% Mo] (at.%). Since the grand potential formulation (Choudhury and Nestler, 2012) has the advantage of being amenable to incorporation of thermodynamic data for all the relevant phases, it is our phase field model of choice for this study. Our attempt is aimed at identifying specific gaps between theory/computation and experiments that may be addressed through future research. A comparison of coarsening rate from our 3D simulations with the experimentally observed rate has led to an insight into possible inaccuracies in data available for this system. In particular, it has pointed to the possibility that the curvature of the free energy surface (for the α phase) being overestimated by ThermoCalc.