Abstract
Via fast differential scanning calorimetry using an Au-based glass as an example, we show that metallic glasses should be classified into two types of amorphous/monolithic glass. The first type, termed self-doped glass (SDG), forms quenched-in nuclei or nucleation precursors upon cooling, whereas in the so-called chemically homogeneous glass (CHG) no quenched-in structures are found. For the Au-based glass investigated, the critical cooling and heating rates for the SDG are 500 K s−1 and 20,000 K s−1, respectively; for the CHG they are 4000 K s−1 and 6000 K s−1. The similarity in the critical rates for CHG, so far not reported in literature, and CHG’s tendency towards stochastic nucleation underline the novelty of this glass state. Identifying different types of metallic glass, as is possible by advanced chip calorimetry, and comparing them with molecular and polymeric systems may help to elaborate a more generalized glass theory and improve metallic glass processing.
Highlights
Via fast differential scanning calorimetry using an Au-based glass as an example, we show that metallic glasses should be classified into two types of amorphous/monolithic glass
In14, one of the authors of this paper reported on the crystallization kinetics of an Au-based bulk metallic glass (Au49Ag5.5Pd2.3Cu26.9Si16.337), and constructed, via isothermal measurements in the millisecond range, complete time–temperature–transformation (TTT) diagrams of crystallization in the undercooled/supercooled liquid range upon cooling and heating
We show that quenchedin nuclei or nucleation precursors form in the self-doped glass (SDG) upon cooling at medium rates, which generates significant differences in the critical cooling and heating rates
Summary
Via fast differential scanning calorimetry using an Au-based glass as an example, we show that metallic glasses should be classified into two types of amorphous/monolithic glass. Since the introduction of non-adiabatic chip calorimetry[18,19] and its commercialization[20,21], calorimetric measurements at defined cooling and heating conditions have been possible using fast differential scanning calorimetry (FDSC) This technique is frequently used to study glass transition phenomena and nanostructure formation in polymers[22,23,24], molecular glass formers[25], and chalcogenides[26,27,28,29]. In this study we use a newly developed Flash DSC2+ instrument (see Methods) which allows us to perform calorimetric experiments at ultrafast cooling rates of 40,000 Ks−1 and heating rates greater than 60,000 Ks−1 The latter allows us to upquench a certain phase, where up-quenching denotes a heating process that is so rapid that no structural changes occur before melting of the previously frozen phase[36]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
