Coupling of homogeneous and heterogeneous melting kinetics in polycrystalline materials
arXiv:1904.07397
The paper presents a model that simultaneously accounts for homogeneous and heterogeneous melting mechanisms in polycrystalline materials, showing how grain size influences overall melting kinetics and identifying a critical temperature where the dominant mechanism switches.
Abstract
Melting kinetics of polycrystalline materials is analyzed on the basis of a new model which explicitly couples homogeneous and heterogeneous melting mechanisms. The distinct feature of this approach lies in its ability to evaluate not only grain-size-distribution effects on the overall melting kinetics but also competitions between the two melting mechanisms. For the first time, we reveal the three-part structure of temperature-time-transformation diagrams for melting of polycrystalline materials, through which it is possible to determine a critical temperature across which the dominant melting mechanism switches. The critical temperature increases as the mean-grain-diameter decreases following a negative power-law. The results are qualitatively consistent with experimental observations.
1. MD simulation results are deleted. 2. The parameter table is added. 3. Qualitative comparisons with experiments are added. 4. Limitations of the model are added