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Nucleation of stoichiometric compounds from liquid: Role of the kinetic factor

TitleNucleation of stoichiometric compounds from liquid: Role of the kinetic factor
Publication TypeJournal Article
Year of Publication2018
AuthorsSong, H, Sun, Y, Zhang, F, Wang, CZ, Ho, KM, Mendelev, MI
JournalPhysical Review Materials
Date Published02
Type of ArticleArticle
ISBN Number2475-9953
Accession NumberWOS:000425496300001
Keywordscolloids, crystal-nucleation, cu-zr alloys, dynamics, interatomic, interfacial free-energy, Materials Science, potentials, prediction, simulation, surface, transition

The nucleation rate depends on the free-energy barrier and the kinetic factor. While the role of the free energy barrier is a text-book subject, the importance of the kinetic factor is frequently underestimated. In this study, we applied the mean first-passage time method, to obtain the free-energy landscape and kinetic factor directly from the molecular dynamics (MD) simulations of the nucleation of the face-centered cubic (fcc) phase in the pure Ni and the B2 phases in the Ni50Al50 and Cu50Zr50 alloys. The obtained data show that while the free-energy barrier for nucleation is higher in pure Ni the nucleation rate is considerably lower in the Ni50Al50 alloy. This result can be explained by the slow attachment kinetics in the Ni50Al50 alloy, which was related to the ordered nature of the B2 phase. Even smaller fraction of the antisite defects in the Cu50Zr50 alloy leads to such a slow attachment kinetics that the nucleation is never observed for this alloy in the course of theMD simulation. This is consistent with the experimental facts that the Cu50Zr50 alloy is a good glass forming alloy and the Ni50Al50 alloy is not. Thus the present study demonstrates that the atom attachment rate can be the critical factor that controls the nucleation process under certain conditions.

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Structures and Dynamics