Unusual Crystallization Behavior Close to the Glass Transition

Caroline Desgranges and Jerome Delhommelle
Phys. Rev. Lett. 120, 115701 – Published 15 March 2018

Abstract

Using molecular simulations, we shed light on the mechanism underlying crystal nucleation in metal alloys and unravel the interplay between crystal nucleation and glass transition, as the conditions of crystallization lie close to this transition. While decreasing the temperature of crystallization usually results in a lower free energy barrier, we find an unexpected reversal of behavior for glass-forming alloys as the temperature of crystallization approaches the glass transition. For this purpose, we simulate the crystallization process in two glass-forming Copper alloys, Ag6Cu4, which has a positive heat of mixing, and CuZr, characterized by a large negative heat of mixing. Our results allow us to identify this unusual behavior as directly correlated with a nonmonotonic temperature dependence for the formation energy of connected icosahedral structures, which are incompatible with crystalline order and impede the development of the crystal nucleus, leading to an unexpectedly larger free energy barrier at low temperature. This, in turn, promotes the formation of a predominantly closed-packed critical nucleus, with fewer defects, thereby suggesting a new way to control the structure of the crystal nucleus, which is of key importance in catalysis.

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  • Received 5 June 2017
  • Revised 13 February 2018

DOI:https://doi.org/10.1103/PhysRevLett.120.115701

© 2018 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Caroline Desgranges and Jerome Delhommelle

  • Department of Chemistry, University of North Dakota, Grand Forks, North Dakota 58202, USA

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Issue

Vol. 120, Iss. 11 — 16 March 2018

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