Shear susceptibility – A universal integral parameter relating the shear softening, heat effects, anharmonicity of interatomic interaction and “defect” structure of metallic glasses

2017 ◽  
Vol 87 ◽  
pp. 1-5 ◽  
Author(s):  
A.S. Makarov ◽  
Yu.P. Mitrofanov ◽  
G.V. Afonin ◽  
N.P. Kobelev ◽  
V.A. Khonik
Keyword(s):  
Metallic Glasses ◽  
Defect Structure ◽  
Interatomic Interaction ◽  
Integral Parameter ◽  
Heat Effects ◽  
Universal Integral ◽  
Softening Heat

scholarly journals Metallic Glasses: A New Approach to the Understanding of the Defect Structure and Physical Properties

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 605 ◽  
Author(s):  
Vitaly Khonik ◽  
Nikolai Kobelev
Keyword(s):  
Shear Modulus ◽  
Physical Properties ◽  
Experimental Verification ◽  
Metallic Glasses ◽  
Structural Relaxation ◽  
Defect Structure ◽  
Relaxation Phenomena ◽  
Volume Changes ◽  
New Approach ◽  
Heat Effects

The work is devoted to a brief overview of the Interstitialcy Theory (IT) as applied to different relaxation phenomena occurring in metallic glasses upon structural relaxation and crystallization. The basic hypotheses of the IT and their experimental verification are shortly considered. The main focus is given on the interpretation of recent experiments on the heat effects, volume changes and their link with the shear modulus relaxation. The issues related to the development of the IT and its relationship with other models on defects in metallic glasses are discussed.

scholarly journals 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

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 417 ◽  
Author(s):  
Andrei Makarov ◽  
Gennadii Afonin ◽  
Yurii Mitrofanov ◽  
Nikolai Kobelev ◽  
Vitaly Khonik
Keyword(s):  
Metallic Glasses ◽  
Liquid State ◽  
Supercooled Liquid ◽  
Shear Moduli ◽  
Thermally Activated ◽  
Supercooled Liquid State ◽  
Heat Effects ◽  
Temperature Dependences ◽  
Defect System ◽  
Kinetics Of

We show that the kinetics of endothermal and exothermal effects occurring in the supercooled liquid state and upon crystallization of metallic glasses can be well reproduced using temperature dependences of their shear moduli. It is argued that the interrelation between the heat effects and shear modulus relaxation reflects thermally activated evolution of interstitial-type defect system inherited from the maternal melt.

On the nature of heat effects and shear modulus softening in metallic glasses: A generalized approach

2014 ◽  
Vol 115 (3) ◽  
pp. 033513 ◽  
Author(s):  
N. P. Kobelev ◽  
V. A. Khonik ◽  
A. S. Makarov ◽  
G. V. Afonin ◽  
Yu. P. Mitrofanov
Keyword(s):  
Shear Modulus ◽  
Metallic Glasses ◽  
Heat Effects

Thermodynamic approach for the understanding of the kinetics of heat effects induced by structural relaxation of metallic glasses

2021 ◽  
Author(s):  
Andrey Makarov ◽  
Gennadii V Afonin ◽  
Alexander S Aronin ◽  
Nikolai Kobelev ◽  
Vitaly A Khonik
Keyword(s):  
Shear Modulus ◽  
Metallic Glasses ◽  
Structural Relaxation ◽  
Entropy Change ◽  
Free Energy Barrier ◽  
Novel Approach ◽  
Heat Effects ◽  
Kinetics Of ◽  
Good Agreement ◽  
Non Equilibrium

Abstract We present a novel approach to the understanding of heat effects induced by structural relaxation of metallic glasses. The key idea consists in the application of a general thermodynamic equation for the entropy change due to the evolution of a non-equilibrium part of a complex system. This non-equilibrium part is considered as a defect subsystem of glass and its evolution is governed by local thermoactivated rearrangements with a Gibbs free energy barrier proportional to the high-frequency shear modulus. The only assumption on the nature of the defects is that they should provide a reduction of the shear modulus – a diaelastic effect. This approach allows to determine glass entropy change upon relaxation. On this basis, the kinetics of the heat effects controlled by defect-induced structural relaxation is calculated. A very good agreement between the calculation and specially performed calorimetric and shear modulus measurements on three metallic glasses is found.

Determination of the thermodynamic potentials of metallic glasses and their relation to the defect structure

2021 ◽  
Author(s):  
Andrey Makarov ◽  
Gennadii V Afonin ◽  
Jichao Qiao ◽  
Alexander Glezer ◽  
Nikolai Kobelev ◽  
...  
Keyword(s):  
Metallic Glasses ◽  
Defect Structure ◽  
Thermodynamic Potentials

On the origin of heat effects and shear modulus changes upon structural relaxation and crystallization of metallic glasses

2017 ◽  
Vol 475 ◽  
pp. 48-52 ◽  
Author(s):  
G.V. Afonin ◽  
Yu.P. Mitrofanov ◽  
A.S. Makarov ◽  
N.P. Kobelev ◽  
V.A. Khonik
Keyword(s):  
Shear Modulus ◽  
Metallic Glasses ◽  
Structural Relaxation ◽  
Heat Effects

scholarly journals Towards understanding of heat effects in metallic glasses on the basis of macroscopic shear elasticity

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Y. P. Mitrofanov ◽  
D. P. Wang ◽  
A. S. Makarov ◽  
W. H. Wang ◽  
V. A. Khonik
Keyword(s):  
Metallic Glasses ◽  
Heat Effects ◽  
Shear Elasticity

Structure of Shear Bands in Zirconium-Based Metallic Glasses Observed by Transmission Electron Microscopy

2002 ◽  
Vol 754 ◽  
Author(s):  
Xiaofeng Gu ◽  
Kenneth J. T. Livi ◽  
Todd C. Hufnagel
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Metallic Glasses ◽  
Defect Structure ◽  
Shear Bands ◽  
Tem Analysis ◽  
Transmission Electron ◽  
Before And After ◽  
High Resolution Tem ◽  
Band Spacing

ABSTRACTWe have used transmission electron microscopy (TEM) to investigate the structure of shear bands produced by bending electron-transparent Zr52.5Cu17.9Ni14.6Al10Ti5 metallic glass specimens. Shear bands were located by comparing the structure of the specimens before and after deformation. The shear band spacing is influenced by the structure of the specimen; portions of the specimen with a significant population of nanocrystals show a smaller separation between shear bands. Quantitative high resolution TEM analysis based on ratio technique has been used to explore the defect structure in shear bands. High density and void-like defects with size of about 1 nm were found in shear bands formed in both amorphous and nanocrystalline areas. A simple model was proposed to explain the formation of these defects.

Electron Microscope Observations of Mechanical Metamorphism in Iron Meteorites

1970 ◽  
Vol 28 ◽  
pp. 488-489
Author(s):  
D. Faulkner ◽  
G.W. Lorimer ◽  
H.J. Axon
Keyword(s):  
Electron Microscope ◽  
Defect Structure ◽  
Shock Loading ◽  
List Type ◽  
Iron Meteorites

It is now generally accepted that meteorites are fragments produced by the collision of parent bodies of asteroidal dimensions. Optical metallographic evidence suggests that there exists a group of iron meteorites which exhibit structures similar to those observed in explosively shock loaded iron. It seems likely that shock loading of meteorites could be produced by preterrestrial impact of their parent bodies as mentioned above.We have therefore looked at the defect structure of one of these meteorites (Trenton) and compared the results with those made on a) an unshocked ‘standard’ meteorite (Canyon Diablo)b) an artificially shocked ‘standard’ meteorite (Canyon Diablo) andc) an artificially shocked specimen of pure α-iron.

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