Abstract
In this work we show that through thermal expansion am measured by real-time diffraction using synchrotron light in transmission, the "glass transition Tg" and for the first time, the "quenched-in free volume" can be quantitatively measured in bulk metallic glasses. This was impossible previously as metallic glasses with crystallisation temperature Tx near Tg crystallized during real-time diffraction experiments. This limitation does not hold for newly developed bulk metallic glasses (BMGs) with large supercooled regions ΔT = Tx-T g. Under such conditions, the variation, Δαth, of the volume coefficient of thermal expansion has been measured by diffraction near Tg for a number of bulk metallic glasses. A clear Δαth has been detected in the same glass transition temperature range of ΔCp measured by DSC calorimetry in particular for Pd-based, Zr-based and Hf-based bulk glasses. The directly measured quenched-in free-volume content Vf is reported here for the first time is found, as expected, to depend on the quench rate and anneals out just below Tg.
Original language | English |
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Pages (from-to) | 23-28 |
Number of pages | 6 |
Journal | Journal of Metastable and Nanocrystalline Materials |
Volume | 20-21 |
DOIs | |
Publication status | Published - 2004 |
Event | Proceedings of the 10th International Symposium on Metastable Mechanically Alloyed and Nanocrystalline Materials (ISMANAM-2002) - Foz do Ifuacu, Brazil Duration: 2003 Aug 24 → 2003 Aug 28 |
Keywords
- Bulk Metallic Glasses
- Free Volume
- Glass Transition Temperature
- Synchrotron Radiation
ASJC Scopus subject areas
- Materials Science (miscellaneous)
- Materials Science(all)
- Condensed Matter Physics
- Physical and Theoretical Chemistry