Abstract
It is shown that all heat effects taking place upon annealing of a metallic glass within the glassy and supercooled liquid states, i.e. heat release below the glass transition temperature and heat absorption above it, as well as crystallization-induced heat release, are related to the macroscopic shear elasticity. The underlying physical reason can be understood as relaxation in the system of interstitialcy-type ”defects” (elastic dipoles) frozen-in from the melt upon glass production.
Highlights
It is shown that all heat effects taking place upon annealing of a metallic glass within the glassy and supercooled liquid states, i.e. heat release below the glass transition temperature and heat absorption above it, as well as crystallization-induced heat release, are related to the macroscopic shear elasticity
Rather clear evidence was obtained that the heat release and heat absorption in metallic glasses below the crystallization onset temperature are determined by the macroscopic shear elasticity, which is probed by measurements of the shear modulus[10,11,12,13]
The excellent fit of Eq (2) to the experimental heat flow provides support that the heat effects due to both structural relaxation and crystallization of glass are intrinsically connected with the relaxation in the system of frozen-in dumbbell interstitial-type “defects”
Summary
It is shown that all heat effects taking place upon annealing of a metallic glass within the glassy and supercooled liquid states, i.e. heat release below the glass transition temperature and heat absorption above it, as well as crystallization-induced heat release, are related to the macroscopic shear elasticity. A well known interpretation of heat effects in metallic glasses is based on the free volume notion, which states that a change of the “free volume” below or above Tg (within the non-crystalline state) yields release or absorption of the internal energy[6,7] This hypothesis provides only qualitative interpretation of calorimetric data[7,8] and was repeatedly criticized It was suggested that melting of simple metallic crystals takes www.nature.com/scientificreports/
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