Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published February 11, 2020 | Supplemental Material + Published
Journal Article Open

Observation of an apparent first-order glass transition in ultrafragile Pt–Cu–P bulk metallic glasses


An experimental study of the configurational thermodynamics for a series of near-eutectic Pt_(80-x)Cu_xP₂₀ bulk metallic glass-forming alloys is reported where 14 < x < 27. The undercooled liquid alloys exhibit very high fragility that increases as x decreases, resulting in an increasingly sharp glass transition. With decreasing x, the extrapolated Kauzmann temperature of the liquid, T_K, becomes indistinguishable from the conventionally defined glass transition temperature, T_g. For x < 17, the observed liquid configurational enthalpy vs. T displays a marked discontinuous drop or latent heat at a well-defined freezing temperature, T_(gm). The entropy drop for this first-order liquid/glass transition is approximately two-thirds of the entropy of fusion of the crystallized eutectic alloy. Below T_(gm), the configurational entropy of the frozen glass continues to fall rapidly, approaching that of the crystallized eutectic solid in the low T limit. The so-called Kauzmann paradox, with negative liquid entropy (vs. the crystalline state), is averted and the liquid configurational entropy appears to comply with the third law of thermodynamics. Despite their ultrafragile character, the liquids at x = 14 and 16 are bulk glass formers, yielding fully glassy rods up to 2- and 3-mm diameter on water quenching in thin-wall silica tubes. The low Cu content alloys are definitive examples of glasses that exhibit first-order melting.

Additional Information

© 2020 National Academy of Sciences. Published under the PNAS license. Contributed by William L. Johnson, December 15, 2019 (sent for review September 20, 2019; reviewed by John H. Perepezko and Frans Spaepen. PNAS first published January 28, 2020. We acknowledge the NSF for partial support of the present work under Grant DMR-1710744 and support of S.L.C. under the NSF Graduate Research Fellowship Program (Grant DGE-1144469). We acknowledge Prof. Jorg Loffler of Eidgenössische Technische Hochschule Zürich for providing the high-resolution SEM images and chemical analysis included in SI Appendix, Supplemental Materials. Data Availability: All data used in the paper are compiled in SI Appendix. SI Appendix, Table S1 lists all data for the isothermal and constant heating rate experiments. Author contributions: J.H.N. and W.L.J. designed research; J.H.N., S.L.C., and A.H. performed research; J.H.N., S.L.C., A.H., and W.L.J. analyzed data; and J.H.N., S.L.C., and W.L.J. wrote the paper. Reviewers: J.H.P., University of Wisconsin–Madison; and F.S., Harvard University. The authors declare no competing interest. This article contains supporting information online at https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.1916371117/-/DCSupplemental.

Attached Files

Published - 2779.full.pdf

Supplemental Material - pnas.1916371117.sapp.pdf


Files (5.1 MB)
Name Size Download all
3.7 MB Preview Download
1.3 MB Preview Download

Additional details

August 22, 2023
October 19, 2023