Universal relationship between crystallization-induced changes of the shear modulus and heat release in metallic glasses

Heat Effects Occurring in the Supercooled Liquid State and Upon Crystallization of Metallic Glasses as a Result of Thermally Activated Evolution of Their Defect Systems

“…[19]. It was later found that the whole excess enthalpy (heat content) of glass with respect to the maternal crystal (i.e., the difference between the heat contents of the glassy and crystalline states) within the IT framework is related to the elastic energy of interstitial-type defect system and this energy is fully released as heat when the defect concentration drops down to zero as a result of crystallization [20]. Thus, all exo-and endothermal heat effects occurring upon structural relaxation and crystallization can be considered as different sides of the same process-a change of interstitial-type defect concentration.…”

Boson Heat Capacity Peak in Metallic Glasses: Evidence of the Same Defect‐Induced Heat Absorption Mechanism in Structurally Relaxed and Partially Crystallized States

“…In particular, the IT provides surprisingly exact description of the kinetics of heat release/absorption both upon structural relaxation and crystallization of MGs . Since the interstitial defect concentration is tightly related with the unrelaxed shear modulus, the heat effects are controlled by the relaxation of the shear elasticity . Because of this intrinsic relationship, the BP height depends on shear modulus changes upon structural relaxation and can be related to the changes of the defect concentration calculated within the framework of the IT …”

“…Meanwhile, it was recently argued that the excess internal energy of glass with respect to the crystal is predominantly determined by the elastic shear energy of interstitialcy defect strain field, which disappears upon crystallization when c falls down to zero. It is this energy, which is released as the heat of crystallization . Then, the BP height should linearly decrease with a reduction of the defect concentration upon continued crystallization.…”

Relationship Between the Boson Heat Capacity Peak and the Excess Enthalpy of a Metallic Glass

“…It was found for a number of MGs that, indeed, to an accuracy ≈10 (ref. ). Accepting an expression for and remembering that at constant pressure Q equals to the excess enthalpy of the glass , one arrives at where ρ is the density .…”

“…On the other hand, it was found that the excess internal energy of MGs with respect to the maternal crystal is mostly related to interstitial‐type defects and can be easily expressed through the shear moduli G and μ . Since the volume changes occurring upon crystallization give insignificant contributions to the internal energy and can be omitted, the energy should be approximately equal to the heat of crystallization Q . It was found for a number of MGs that, indeed, to an accuracy ≈10 (ref.…”