scholarly journals Influence of HPT Deformation on the Structure and Properties of Amorphous Alloys

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 415 ◽  
Author(s):  
Dmitry Gunderov ◽  
Vasily Astanin
Keyword(s):  
Amorphous Phase ◽  
Amorphous Alloys ◽  
Amorphous Materials ◽  
Structural Changes ◽  
High Pressure Torsion ◽  
Shear Bands ◽  
Physical And Mechanical Properties ◽  
Chemical Separation ◽  
Structure And Properties ◽  
Processing Regimes

Recent studies showed that structural changes in amorphous alloys under high pressure torsion (HPT) are determined by their chemical composition and processing regimes. For example, HPT treatment of some amorphous alloys leads to their nanocrystallization; in other alloys, nanocrystallization was not observed, but structural transformations of the amorphous phase were revealed. HPT processing resulted in its modification by introducing interfaces due to the formation of shear bands. In this case, the alloys after HPT processing remained amorphous, but a cluster-type structure was formed. The origin of the observed changes in the structure and properties of amorphous alloys is associated with the chemical separation and evolution of free volume in the amorphous phase due to the formation of a high density of interfaces as a result of HPT processing. Amorphous metal alloys with a nanocluster structure and nanoscale inhomogeneities, representatives of which are nanoglasses, significantly differ in their physical and mechanical properties from conventional amorphous materials. The results presented in this review show that the severe plastic deformation (SPD) processing can be one of the efficient ways for producing a nanocluster structure and improving the properties of amorphous alloys.

scholarly journals Specific Features of Structure Transformation and Properties of Amorphous-Nanocrystalline Alloys

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 358 ◽  
Author(s):  
Alexandr Aronin ◽  
Galina Abrosimova
Keyword(s):  
Amorphous Phase ◽  
Metallic Glasses ◽  
Amorphous Alloys ◽  
Structural Changes ◽  
Shear Bands ◽  
Component Composition ◽  
Amorphous Structure ◽  
Structure Evolution ◽  
Current State ◽  
Heterogeneous Phase

This work is devoted to a brief overview of the structure and properties of amorphous-nanocrystalline metallic alloys. It presents the current state of studies of the structure evolution of amorphous alloys and the formation of nanoglasses and nanocrystals in metallic glasses. Structural changes occurring during heating and deformation are considered. The transformation of a homogeneous amorphous phase into a heterogeneous phase, the dependence of the scale of inhomogeneities on the component composition, and the conditions of external influences are considered. The crystallization processes of the amorphous phase, such as the homogeneous and heterogeneous nucleation of crystals, are considered. Particular attention is paid to a volume mismatch compensation on the crystallization processes. The effect of changes in the amorphous structure on the forming crystalline structure is shown. The mechanical properties in the structure in and around shear bands are discussed. The possibility of controlling the structure of fully or partially crystallized samples is analyzed for creating new materials with the required physical properties.

scholarly journals Amorphous-Nanocrystalline Composites Prepared by High-Pressure Torsion

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 511 ◽  
Author(s):  
Inga Permyakova ◽  
Alex Glezer
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Hydrostatic Pressure ◽  
Severe Plastic Deformation ◽  
Amorphous Alloys ◽  
Preparation Method ◽  
High Pressure Torsion ◽  
Structure And Properties ◽  
Nanocrystalline Composites

This article presents systematic studies of the preparation method and the specific features of the changes in the structure and properties of amorphous-nanocrystalline composites formed from melt-quenched ribbons of iron- and cobalt-based amorphous alloys and the Cu-Nb crystalline nanolaminates by severe plastic deformation by torsion in the Bridgeman chamber at high quasi-hydrostatic pressure.

scholarly journals The influence of rolling and high-pressure torsion in the Bridgman chamber on the quantitative characteristics of shear bands in an amorphous Zr-based alloy

2021 ◽  
pp. 67-74
Author(s):  
I. A. Khriplivets ◽  
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Metallic Glasses ◽  
Amorphous Alloys ◽  
High Pressure Torsion ◽  
Shear Bands ◽  
Quantitative Description ◽  
Polished Surface ◽  
Deformation Method ◽  
Quantitative Characteristics

Amorphous alloys based on metal components demonstrate a unique ability to realize plastic deformation under the influence of external mechanical stresses. Influenced by substantial degrees of plastic deformation in alloys, one can observe shear bands (SB) in the form of rough lines on the polished surface of the sample. The concept of shear band formation in amorphous metallic glasses varies greatly from plastic deformation processes in crystalline metals and alloys. Unlike crystalline metals, amorphous metallic glasses can exist in a spectrum of structural states with accompanying mechanical, thermodynamic, and physical properties of materials. The formation and evolution of shear bands control the fluidity and plasticity of almost all metallic glasses at room temperature, and in many cases, the formation of dominant shear bands rapidly leads to failure. The literature does not contain any rigorous quantitative description of SB main parameters, which could adequately describe in the analytical form the process of plastic deformation of amorphous alloys, similar to the dislocation and disclination theories of plastic deformation of crystals. An open question remains how the transition from macroscopic deformation to severe plastic deformations of amorphous alloys affects the key SB characteristics. In this work, using the method of optical profilometry, the author studied in detail the quantitative characteristics of the steps formed by shear bands on the surface of deformed samples of the massive amorphous alloy Zr60Ti2Nb2Cu18.5Ni7.5Al10 after high-pressure torsion (HPT) and after rolling. The study identified that the design of shear bands depends on the deformation method and showed that the magnitude of deformation had the controlling effect on the shear bands thickness (the height of the steps). The transition from deformation by rolling (e=0.4) to plastic deformation during HPT (e=2.6) leads to the threefold increase in the power of shear bands and the average distance between them.

AEM analysis of crystallization in Ti-based amorphous alloys

1983 ◽  
Vol 41 ◽  
pp. 270-271
Author(s):  
A.R. Pelton ◽  
A.F. Marshall ◽  
Y.S. Lee
Keyword(s):  
Magnetic Properties ◽  
Amorphous Alloys ◽  
Amorphous Materials ◽  
Isothermal Annealing ◽  
Amorphous Matrix ◽  
Nucleation And Growth ◽  
Current Interest ◽  
Amorphous Films ◽  
Electrical And Magnetic Properties

Amorphous materials are of current interest due to their desirable mechanical, electrical and magnetic properties. Furthermore, crystallizing amorphous alloys provides an avenue for discerning sequential and competitive phases thus allowing access to otherwise inaccessible crystalline structures. Previous studies have shown the benefits of using AEM to determine crystal structures and compositions of partially crystallized alloys. The present paper will discuss the AEM characterization of crystallized Cu-Ti and Ni-Ti amorphous films.Cu60Ti40: The amorphous alloy Cu60Ti40, when continuously heated, forms a simple intermediate, macrocrystalline phase which then transforms to the ordered, equilibrium Cu3Ti2 phase. However, contrary to what one would expect from kinetic considerations, isothermal annealing below the isochronal crystallization temperature results in direct nucleation and growth of Cu3Ti2 from the amorphous matrix.

Structure and properties of compact articles from high-alloyed iron powder with adding of boron nitride

2020 ◽  
pp. 39-48
Author(s):  
B. O. Bolshakov ◽  
◽  
R. F. Galiakbarov ◽  
A. M. Smyslov ◽  
◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Boron Nitride ◽  
Grain Boundary ◽  
Bending Strength ◽  
Physical And Mechanical Properties ◽  
Operating Conditions ◽  
Structure And Properties ◽  
Steam Turbines ◽  
Friction Forces ◽  
Wide Range

The results of the research of structure and properties of a composite compact from 13 Cr – 2 Мо and BN powders depending on the concentration of boron nitride are provided. It is shown that adding boron nitride in an amount of more than 2% by weight of the charge mixture leads to the formation of extended grain boundary porosity and finely dispersed BN layers in the structure, which provides a high level of wearing properties of the material. The effect of boron nitride concentration on physical and mechanical properties is determined. It was found that the introduction of a small amount of BN (up to 2 % by weight) into the compacts leads to an increase in plasticity, bending strength, and toughness by reducing the friction forces between the metal powder particles during pressing and a more complete grain boundary diffusion process during sintering. The formation of a regulated structure-phase composition of powder compacts of 13 Cr – 2 Mо – BN when the content of boron nitride changes in them allows us to provide the specified physical and mechanical properties in a wide range. The obtained results of studies of the physical and mechanical characteristics of the developed material allow us to reasonably choose the necessary composition of the powder compact for sealing structures of the flow part of steam turbines, depending on their operating conditions.

scholarly journals High density of shear bands in the Vitreloy bulk metallic glass subjected to high-pressure torsion

2021 ◽  
Vol 1008 ◽  
pp. 012031
Author(s):  
Vasily Astanin ◽  
Dmitry Gunderov ◽  
Zhi Qiang Ren ◽  
Ruslan Valiev ◽  
Jing Tao Wang
Keyword(s):  
High Pressure ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
High Pressure Torsion ◽  
Shear Bands ◽  
High Density

Plastic Deformation-Induced Nanocrystalline Aluminum in Al-Based Amorphous Alloys

1993 ◽  
Vol 321 ◽  
Author(s):  
H. Chen ◽  
Y. He ◽  
G. J. Shiflet ◽  
S. J. Poon
Keyword(s):  
Plastic Deformation ◽  
Amorphous Alloy ◽  
Shear Band ◽  
Thin Layer ◽  
Ball Milling ◽  
Direct Observation ◽  
Amorphous Alloys ◽  
Shear Bands ◽  
Amorphous Ribbons ◽  
Nanocrystalline Aluminum

ABSTRACTWe report the first direct observation of crystallization induced in the slipped planes of aluminum based amorphous alloys by bending the amorphous ribbons. Nanometer-sized crystalline precipitates are found exclusively within a thin layer (shear band) in the slipped planes extending across the deformed amorphous alloy ribbons. It is also found that the nanocrystalline aluminum can be produced by ball-Milling. It is likely that local atomic rearrangements within the shear bands create the nanocrystals which appear after plastic deformation.

Study of Properties of Expanded Graphite – Polymer Porous Composite by Acoustic Emission Method

2013 ◽  
Vol 58 (4) ◽  
pp. 1331-1336 ◽  
Author(s):  
J. Berdowski ◽  
S. Berdowska ◽  
F. Aubry
Keyword(s):  
Acoustic Emission ◽  
Structural Changes ◽  
Structural Characteristics ◽  
Physical And Mechanical Properties ◽  
Expanded Graphite ◽  
Composite Membranes ◽  
Acoustic Emission Method ◽  
Emission Method ◽  
Graphite Composite ◽  
Wide Range

Abstract The purpose of this paper was to investigate the physical and mechanical properties of compressed expanded graphite (CEG) and their porous derivatives after impregnation, polymerization; and carbonization by the use of acoustic emission method (AE). The mechanical and structural characteristics of compressed expanded graphite and their three groups of porous composites after each technological process are presented and discussed. The measurements of acoustic emission parameters in these materials were carried out at wide range of frequency of the waves (0.1÷2.5 MHz). The changes of two of parameters: - AE pulses counts rate and spectrum distribution of AE waves - are presented in this paper. The analysis of the respective parameters AE also gives possibility to determine the micro- and macro structural changes of materials at different levels of technological processes. Applications of these materials as catalysts with high specific surface make them very interesting subject of study. Also compressed expanded graphite composite membranes prepared from furfuryl alcohol polymers are promising for gas separation.

scholarly journals High pressure torsion induced structural transformations in Ti- and Zr-based amorphous alloys

2018 ◽  
Vol 447 ◽  
pp. 012052 ◽  
Author(s):  
D V Gunderov ◽  
E V Boltynjuk ◽  
E V Ubyivovk ◽  
A A Churakova ◽  
G E Abrosimova ◽  
...  
Keyword(s):  
High Pressure ◽  
Amorphous Alloys ◽  
High Pressure Torsion ◽  
Structural Transformations
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