Dissolution kinetics of irregular second phase in as-cast Cu-Ti alloys via a multi-particle dissolution model

Abstract

The morphology of the second phases formed during the solidification is irregular in many alloy systems, making precise simulation of their dissolved evolution difficult. In this work, a multi-particle spherical log-normal distribution was used to simulate the dissolution of such irregular second phase and took the as-cast Cu-Ti alloy as a case study. The dissolution of the as-cast Cu4Ti phase was simulated via a multi-particle dissolution model integrating the CALPHAD-based diffusion theory (CALPHAD: CALculation of PHAse Diagrams) and high-throughput calculations. The 5041 sub-models (spherical log-normal distributions) replacing the size distribution of the as-cast Cu4Ti phase were initially generated based on the mass balance. Then, 2.5×106 data points in 491 sub-models selected from 5041 sub-models were calculated to fit the experimental DSC curves based on the energy conservation, and the best-fitted sub-model could be determined finally. Based on this sub-model, the volumetric and energetic evolution of the as-cast Cu4Ti phase during various dissolution processes could be predicted, and the simulated results were confirmed to be in agreement with the present experimental results. Also, a counterintuitive self-coarsening phenomenon of the Cu4Ti phase has been observed during heating, which has been approved in the experimental work.