scholarly journals Dissolution of Ag Precipitates in the Cu–8wt.%Ag Alloy Deformed by High Pressure Torsion

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 447 ◽  
Author(s):  
Anna Korneva ◽  
Boris Straumal ◽  
Askar Kilmametov ◽  
Robert Chulist ◽  
Grzegorz Cios ◽  
...  
Keyword(s):  
High Pressure ◽  
Volume Fraction ◽  
High Pressure Torsion ◽  
Copper Matrix ◽  
Solubility Limit ◽  
Mixing Enthalpy ◽  
Diffusion Activation Energy ◽  
Second Phase ◽  
Silver Particles ◽  
Initial State

The aim of this work was to study the influence of severe plastic deformation (SPD) on the dissolution of silver particles in Cu–8wt.%Ag alloys. In order to obtain different morphologies of silver particles, samples were annealed at 400, 500 and 600 °C. Subsequently, the material was subjected to high pressure torsion (HPT) at room temperature. By means of scanning and transmission electron microscopy, as well as X-ray diffraction techniques, it was found that during SPD, the dissolution of second phase was strongly affected by the morphology and volume fraction of the precipitates in the initial state. Small, heterogeneous precipitates of irregular shape dissolved more easily than those of large size, round-shaped and uniform composition. It was also found that HPT led to the increase of solubility limit of silver in the copper matrix as the result of dissolution of the second phase. This unusual phase transition is discussed with respect to diffusion activation energy and mixing enthalpy of the alloying elements.

X-Ray Analysis of α and ω – Phases of Ti, Subjected to High-Pressure Torsion

2010 ◽  
Vol 667-669 ◽  
pp. 187-192 ◽  
Author(s):  
Vil D. Sitdikov ◽  
Igor V. Alexandrov ◽  
Jan T. Bonarski
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
Crystallographic Texture ◽  
Volume Fraction ◽  
High Pressure Torsion ◽  
Initial State ◽  
X Ray ◽  
Ray Patterns

This paper presents the results of experimental X-ray structural analyses of both the evolution structure and the crystallographic one in the volume of Ti samples, subjected to the Severe Plastic Deformation (SPD), realized by torsion under high pressure equal to 6 GPa at temperature 298 K. The investigations have been carried out on the disk-shaped samples with the radius of 20 mm in an initial state (the as-received state) and in the states after 0.1, 0.5, 1 and 5 rotations by High-Pressure Torsion (HPT). In the result the evolution mechanisms of the general X-ray patterns, the volume fraction of phases, the character of preferred orientations, as well as the activity of various slip and twinning systems in α- and ω-phases, depending on the SPD degree have been found out. The received results allow explaining and forecasting the behavior of nanostructured Ti, considering the parameters of its microstructure and crystallographic texture.

Magnetic Characterization of SUS316L Deformed by High Pressure Torsion

2011 ◽  
Vol 239-242 ◽  
pp. 1300-1303
Author(s):  
Hong Cai Wang ◽  
Minoru Umemoto ◽  
Innocent Shuro ◽  
Yoshikazu Todaka ◽  
Ho Hung Kuo
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Stainless Steel ◽  
Phase Transformation ◽  
Austenitic Stainless Steel ◽  
Volume Fraction ◽  
High Pressure Torsion ◽  
Austenitic Matrix ◽  
Magnetic Characterization

SUS316L austenitic stainless steel was subjected to severe plastic deformation (SPD) by the method of high pressure torsion (HPT). From a fully austenitic matrix (γ), HPT resulted in phase transformation from g®a¢. The largest volume fraction of 70% a¢ was obtained at 0.2 revolutions per minute (rpm) while was limited to 3% at 5rpm. Pre-straining of g by HPT at 5rpm decreases the volume fraction of a¢ obtained by HPT at 0.2rpm. By HPT at 5rpm, a¢®g reverse transformation was observed for a¢ produced by HPT at 0.2rpm.

Variation of Microstructure and Mechanical Properties of ZW61 Magnesium Alloy Solidified under Different Pressures

2022 ◽  
Vol 327 ◽  
pp. 3-10
Author(s):  
Shu Sen Wu ◽  
Xiao Gang Fang ◽  
Shu Lin Lü ◽  
Long Fei Liu ◽  
Wei Guo
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Volume Fraction ◽  
Applied Pressure ◽  
Second Phase ◽  
Cast State ◽  
Microstructure And Properties ◽  
Microstructure Refinement ◽  
Porosity Reduction ◽  
Average Grain Size

There is little datum related to microstructure and properties of Mg alloys squeeze-casted with pressure over 200 MPa. In this study, the microstructure and properties of Mg-6Zn-1.4Y (ZW61) alloy solidified under 100MPa to 800MPa were investigated. The results show that a remarkable microstructure refinement and porosity reduction can be reached through solidification under high pressure. The average grain size and the volume fraction of second phase, i.e. quasicrystal I-phase, decrease continuously with the increase of applied pressure. The tensile properties, especially elongation, are obvious enhanced because of the microstructure refinement and castings densification under high pressure. The ultimate tensile strength and elongation of ZW61 alloy in as-cast state are 243 MPa and 18.7% when the applied pressure is 800 MPa, which are increased by 35% and 118% respectively, compared with that of the gravity castings.

Structure and Properties of Grain Boundaries in Submicrocrystalline W Obtained by Severe Plastic Deformation

2009 ◽  
Vol 283-286 ◽  
pp. 629-638 ◽  
Author(s):  
Vladimir V. Popov ◽  
Ruslan Valiev ◽  
E.N. Popova ◽  
A.V. Sergeev ◽  
A.V. Stolbovsky ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Plastic Deformation ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
Grain Boundaries ◽  
High Pressure Torsion ◽  
Submicrocrystalline Structure ◽  
Emission Mössbauer Spectroscopy ◽  
Structure And Properties ◽  
Initial State

Submicrocrystalline structure of W obtained by severe plastic deformation (SPD) by high pressure torsion (5 revolutions of anvils at 4000C) and its thermal stability have been examined by TEM. Grain boundaries of submicrocrystalline W have been studied by the method of the emission Mössbauer spectroscopy in the initial state and after annealing at 400-6000С.

Study on Effect of Different Preparation Process Parameters on Properties and Microstructure of SiO2/Cu Composites

2011 ◽  
Vol 117-119 ◽  
pp. 908-912
Author(s):  
Cui Hua Zheng ◽  
Ke Xing Song ◽  
Xiu Hua Guo ◽  
Yan Jun Zhou
Keyword(s):  
Volume Fraction ◽  
Wear Behavior ◽  
Phase Particle ◽  
Particle Volume Fraction ◽  
Hot Extrusion ◽  
Copper Matrix ◽  
Second Phase ◽  
Matrix Composites ◽  
Particle Volume ◽  
Comprehensive Properties

The SiO2 nanoparticles reinforced Cu-matrix composites were prepared by powder metallurgy technology．The influences of SiO2 volume fraction on the properties of hardness、conductivitity rate and wear behavior of Cu-matrix composites were studied. The results showed that conductivity rate was decreased with the increase of the SiO2 volume fraction；whereas the hardness was increased, then decreased and wear behavior was increased. Sintering an hour of performance was superior to the sintering half an hour.When SiO2 nanoparticle volume fraction was achieved 2.5%, comprehensive properties of SiO2/Cu composite were obviously increased.The microstructures revealed that the second phase particles precipitated dispersedly in copper matrix after hot extrusion. with the increase of the strengthen phase particle volume fraction, nanoparticles appeared together and gathered in grain boundary of copper matrix.

Phase Transformation and Annealing Behavior of SUS 304 Austenitic Stainless Steel Deformed by High Pressure Torsion

2010 ◽  
Vol 654-656 ◽  
pp. 334-337 ◽  
Author(s):  
Innocent Shuro ◽  
Minoru Umemoto ◽  
Yoshikazu Todaka ◽  
Seiji Yokoyama
Keyword(s):  
High Pressure ◽  
Stainless Steel ◽  
Phase Transformation ◽  
Austenitic Stainless Steel ◽  
Volume Fraction ◽  
High Pressure Torsion ◽  
Two Phase ◽  
Annealing Behavior ◽  
304 Austenitic Stainless Steel ◽  
Deformed State

SUS 304 austenitic stainless steel was subjected to severe plastic deformation (SPD) by the method of high pressure torsion (HPT). From a fully austenitic matrix (γ), HPT resulted in phase transformation to give a two phase structure of austenite (γ) and martensite (α') by the transformation γα'. The phase transformation was accompanied by an increase in hardness (Hv) from 1.6 GPa in the as annealed form to 5.4 GPa in the deformed state. Subsequent annealing in temperature range 250oC to 450oC resulted in an increase in both α' volume fraction and hardness (6.4 GPa). Annealing at 600oC resulted in a decrease in α' volume fraction hardness.

scholarly journals DIFFUSIVE AND DISPLACIVE PHASE TRANSFORMATIONS UNDER HIGH PRESSURE TORSION

2019 ◽  
Vol 25 (4) ◽  
pp. 230 ◽  
Author(s):  
Boris Straumal ◽  
Askar Kilmametov ◽  
Andrey Mazilkin ◽  
Olga Kogtenkova ◽  
Brigitte Baretzky ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Plastic Deformation ◽  
Grain Size ◽  
High Pressure ◽  
Phase Composition ◽  
Steady State ◽  
Phase Transformations ◽  
High Pressure Torsion ◽  
Dynamic Equilibrium ◽  
Initial State

<p class="AMSmaintext"><span lang="EN-GB">Severe plastic deformation (SPD) can induce various phase transformations. After a certain strain, the dynamic equilibrium establishes between defects production by an external force and their relaxation (annihilation). The grain size, hardness, phase composition etc. in this steady-state does not depend on the initial state of a material and is, therefore, equifinal. In this review we discuss the competition between precipitation and dissolution of precipitates, amorphization and (nano)crystallization, SPD-induced accelerated mass-transfer, allotropic and martensitic transitions and formation of grain boundary phases.</span></p>

scholarly journals High-Pressure Torsion of Ti: Synchrotron characterization of phase volume fraction and domain sizes

2014 ◽  
Vol 63 ◽  
pp. 012147 ◽  
Author(s):  
Raúl E Bolmaro ◽  
Vitor L Sordi ◽  
Maurizio Ferrante ◽  
Heinz-Günter Brokmeier ◽  
Megumi Kawasaki ◽  
...  
Keyword(s):  
High Pressure ◽  
Volume Fraction ◽  
High Pressure Torsion ◽  
Phase Volume ◽  
Phase Volume Fraction

The Enhanced Kinetics of Precipitation Effects in Ultra Fine Grained Mg Alloys Prepared by High Pressure Torsion

2008 ◽  
Vol 273-276 ◽  
pp. 75-80 ◽  
Author(s):  
Jakub Čížek ◽  
Ivan Procházka ◽  
Bohumil Smola ◽  
Ivana Stulíková ◽  
Vladivoj Očenášek ◽  
...  
Keyword(s):  
High Pressure ◽  
Grain Boundaries ◽  
Volume Fraction ◽  
High Pressure Torsion ◽  
Mg Alloys ◽  
Coarse Grained ◽  
Fine Grained ◽  
Transmission Electron ◽  
Positron Lifetime Spectroscopy ◽  
Kinetics Of

Precipitation effects in ultra fine grained (UFG) lightweight Mg-based alloys were studied in the present work by means of positron lifetime spectroscopy, transmission electron microscopy, and microhardness. The UFG samples with grain size around 100 nm were fabricated by high pressure torsion (HPT). The UFG structure contains a significant volume fraction of grain boundaries and exhibits a high number of lattice defects (mainly dislocations) introduced by severe plastic deformation during the HPT processing. A high dislocation density and volume fraction of grain boundaries enhance the long range diffusion of solute elements. Moreover, dislocations and grain boundaries act as nucleation centers for precipitates. As a consequence, the precipitation effects are facilitated in the UFG alloys compared to the conventional coarse-grained samples. This phenomenon was examined in this work by comparison of the precipitation sequence in Mg alloys with UFG structure and solution treated coarse-grained alloys.

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