Understanding homogeneous nucleation in solidification of aluminum by molecular dynamics simulations
Abstract
Homogeneous nucleation from aluminum (Al) melt was investigated by million-atom molecular dynamics simulations utilizing the second nearest neighbor modified embedded atom method potentials. The natural spontaneous homogenous nucleation from the Al melt was produced without any influence of pressure, free surface effects and impurities. Initially isothermal crystal nucleation from undercooled melt was studied at different constant temperatures, and later superheated Al melt was quenched with different cooling rates. The crystal structure of nuclei, critical nucleus size, critical temperature for homogenous nucleation, induction time, and nucleation rate were determined. The quenching simulations clearly revealed three temperature regimes: sub-critical nucleation, super-critical nucleation, and solid-state grain growth regimes. The main crystalline phase was identified as face-centered cubic, but a hexagonal close-packed (hcp) and an amorphous solid phase were also detected. The hcp phase was created due to the formation of stacking faults during solidification of Al melt. By slowing down the cooling rate, the volume fraction of hcp and amorphous phases decreased. After the box was completely solid, grain growth was simulated and the grain growth exponent was determined for different annealing temperatures.
Recommended Citation
A. Mahata et al., "Understanding homogeneous nucleation in solidification of aluminum by molecular dynamics simulations," Modelling and Simulation in Materials Science and Engineering, vol. 26, no. 2, Institute of Physics - IOP Publishing, Mar 2018.
The definitive version is available at https://doi.org/10.1088/1361-651X/aa9f36
Department(s)
Materials Science and Engineering
Keywords and Phrases
aluminum; homogeneous nucleation; isothermal; molecular dynamics; quenching
International Standard Serial Number (ISSN)
0965-0393; 1361-651X
Document Type
Article - Journal
Document Version
Final Version
File Type
text
Language(s)
English
Rights
© 2018 Institute of Physics - IOP Publishing, All rights reserved.
Creative Commons Licensing
This work is licensed under a Creative Commons Attribution 3.0 License.
Publication Date
01 Mar 2018
Comments
Authors would like to acknowledge the funding support from the National Science Foundation under Grant No. NSF-CMMI 1537170. The authors are grateful for computer time allocation provided by the Extreme Science and Engineering Discovery Environment (XSEDE), award number TG-DMR140008.