The Effect of Solids Microcharacteristics on the Macroscopic Parameters of Plastic Deformation Localization in Metals

2007 ◽  
Vol 345-346 ◽  
pp. 93-96
Author(s):  
Lev Zuev ◽  
Svetlana A. Barannikova
Keyword(s):  
Plastic Deformation ◽  
Direct Relationship ◽  
Metals And Alloys ◽  
Scale Level ◽  
Deformation Localization ◽  
Quasi Particle ◽  
New Approach ◽  
Micro Scale ◽  
Macroscopic Parameters

A new approach is proposed for description of autowave processes responsible for plastic deformation localization in metals and alloys. It is postulated that to a localized flow autowave there corresponds a quasi-particle. The characteristics of the quasi-particle have been determined. A direct relationship has been established between the processes involved in the deformation on a macro- and a micro-scale level.

Grain Boundary Design of Bulk Nanomaterials for Advanced Properties

2015 ◽  
Vol 5 ◽  
pp. 43-54 ◽  
Author(s):  
Ruslan Z. Valiev
Keyword(s):  
Plastic Deformation ◽  
Grain Boundary ◽  
Severe Plastic Deformation ◽  
Grain Boundaries ◽  
Metals And Alloys ◽  
New Approach ◽  
Petch Relation ◽  
Ultrafine Grained ◽  
Grain Boundary Segregations ◽  
Bulk Nanomaterials

Nanostructuring of metals and alloys by severe plastic deformation techniques is an effective way of enhancing their mechanical and functional properties. The features of the nanostructured materials produced by severe plastic deformation (SPD) are stipulated by forming of ultrafine-sized grains as well as by the state of grain boundaries. The concept of grain boundary (GB) design of ultrafine-grained metals and alloys is developed for enhancement of their properties by tailoring grain boundaries of different types (low-angle and high-angle ones, special and random, equilibrium and nonequilibrium) and formation of grain boundary segregations and precipitations by SPD processing. The paper presents experimental data demonstrating the super-strength and “positive” slope of the Hall-Petch relation when passing from micro-to nanostructured state in a number of metallic materials subjected to severe plastic deformation. The nature of the superior strength is associated with new strengthening mechanisms and the difficulty of generation of dislocations from grain boundaries with segregations. This new approach is used for achieving the enhanced strength in several commercial Al and Ti alloys as well as steels subjected to SPD processing.

scholarly journals The mechanics of macro scale level plastic deformation localization

2019 ◽  
Vol 1327 ◽  
pp. 012006
Author(s):  
L B Zuev ◽  
S A Barannikova ◽  
A M Zharmukhambetova
Keyword(s):  
Plastic Deformation ◽  
Scale Level ◽  
Deformation Localization ◽  
Macro Scale

MICRO AND MESO SCALES OF DESCRIPTION CORRESPONDING TO A MODEL OF TISSUE INVASION BY SOLID TUMOURS

2005 ◽  
Vol 15 (11) ◽  
pp. 1667-1683 ◽  
Author(s):  
MIROSŁAW LACHOWICZ
Keyword(s):  
Mathematical Models ◽  
Type Equation ◽  
Reaction Diffusion ◽  
Solid Tumours ◽  
Macroscopic Model ◽  
Scale Level ◽  
Micro Scale ◽  
Tissue Invasion ◽  
Mathematical Relationships ◽  
Meso Scale

In this paper two new mathematical models are proposed that correspond to a macroscopic model of tissue invasion of solid tumours, in terms of a system of reaction-diffusion-chemotaxis equations. The first model is defined at the micro-scale level of a large number of interacting individual entities, and is in terms of a linear (Markov) equation. The second model refers to the meso-scale level of description of test-entities and is given in terms of a bilinear Boltzmann-type equation. Mathematical relationships among these three possible descriptions are formulated. Explicit error estimates are given.

Effect of Hydrogen on the Development of Superplastic Deformation in the Submicrocrystalline Ti–6Al–4V Alloy

2016 ◽  
Vol 838-839 ◽  
pp. 344-349 ◽  
Author(s):  
Galina P. Grabovetskaya ◽  
Ekaterina N. Stepanova ◽  
Ilya V. Ratochka ◽  
I.P. Mishin ◽  
Olga V. Zabudchenko
Keyword(s):  
Solid Solution ◽  
Plastic Deformation ◽  
Flow Stress ◽  
Superplastic Deformation ◽  
Deformation Localization ◽  
Solid Solution Strengthening ◽  
Solution Strengthening ◽  
Hydrogenation Effect

Hydrogenation effect on the development of superplastic deformation in the submicrocrystalline Ti–6Al–4V alloy at temperatures (0.4–0.5)Тmelt is investigated. Hydrogenation of the submicrocrystalline Ti–6Al–4V alloy to 0.26 mass% during superplastic deformation is found to result in solid solution strengthening, plastic deformation localization, and as a consequence, decrease of the deformation to failure. Possible reasons for the decrease of the flow stress and increase of the deformation to failure in the submicrocrystalline Ti–6Al–4V–0.26H alloy during deformation under conditions of superplasticity and simultaneous hydrogen degassing from the alloy are discussed.

Analysis of smallholder farmers’ vulnerability to climate change and variability in south Wollo, north east highlands of Ethiopia: An agro-ecological system-based approach

2021 ◽  
Author(s):  
Yimer Mohammed ◽  
Kindie Tesfaye ◽  
Menfese Tadesse ◽  
Fantaw Yimer
Keyword(s):  
Climate Change ◽  
Adaptive Capacity ◽  
Smallholder Farmers ◽  
Contributing Factors ◽  
Scale Level ◽  
Ecological Zones ◽  
Micro Scale ◽  
Climate Change And Variability ◽  
North East ◽  
Agro Ecological Zones

Abstract Background: Climate change and variability has been significantly affecting the Ethiopian agricultural production and thereby smallholder farmers livelihoods. The level of vulnerability varied across agro-ecological zones (AEZs). Identification of difference in the level of vulnerability of a system is important in selecting appropriate and effective adaption options to climate change. Therefore, the aim of this study was to analyze the level of vulnerability of agricultural communities to climate change and variability at micro-scale level in five agro-ecological zones (AEZs) of south Wollo, north east highlands of Ethiopia. Data was collected from a representative of 502 sample households from five AEZs through multi stage random sampling methods. Focus group discussion and key informant interviews were also carried out to supplement and substantiate the quantitative data. The indicator based approach was used to empirically calculate vulnerability. Principal Component Analysis (PCA) was applied to give weight for indicators and generate index of vulnerability contributing factors. Results: The results showed that each of the vulnerability contributing factors (exposure, sensitivity and adaptive capacity) varied across the AEZs. M3, SM2 and SM3 are the most exposed AEZs but having a relatively better adaptive capacity whereas M1, M2 and M3 are the most sensitive AEZs with relatively low adaptive capacity to climate variability and change. Overall, SM2 is the most vulnerable AEZ which exhibited high sensitivity and low adaptive capacity followed by M1. Conclusions: The study explored sources and levels of vulnerability to each agro-ecology. Since the study is conducted at micro-scale level, it helps decision makers and development partners to have context-specific understanding of the impact of climate change and variability and design appropriate adaptation measures to address the specific situations.

R&D of NanoSPD Materials in Ufa via International Cooperation

2008 ◽  
Vol 584-586 ◽  
pp. 9-15 ◽  
Author(s):  
Tasha Reshetnikova ◽  
Milyausha R. Salakhova ◽  
Zarema A. Safargalina ◽  
Andrey V. Shcherbakov
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
International Cooperation ◽  
Nanostructured Materials ◽  
Metals And Alloys ◽  
Advanced Materials ◽  
Nanostructured Metals ◽  
Innovative Potential ◽  
Technical University ◽  
Competing Technologies

This report presents main achievements of international R&D activities of the Institute of Physics of Advanced Materials of Ufa State Aviation Technical University (Ufa, Russia) with a special attention to the innovative potential of nanostructured metals and alloys produced by severe plastic deformation techniques. Several examples of the first promising applications of bulk nanostructured materials as well as potential competing technologies are considered and discussed.

scholarly journals Studying Deformation Behaviors in Austenitic Stainless Steels within a Temperature Range of 143 K < T < 420 K

2021 ◽  
pp. 22-30
Author(s):  
S. A Barannikova ◽  
A. M Nikonova ◽  
S. V Kolosov
Keyword(s):  
Plastic Deformation ◽  
Plastic Strain ◽  
Strain Localization ◽  
Work Hardening ◽  
Deformation Localization ◽  
Linear Hardening ◽  
Jerky Flow ◽  
Temperature Range ◽  
Α Phase ◽  
Flow Stage

This work deals with studying staging and macroscopic strain localization in austenitic stainless steel 12Kh18N9T within a temperature range of 143 K < T < 420 K. The visualization and evolution of macroscopic localized plastic deformation bands at different stages of work hardening were carried out by the method of the double-exposure speckle photography (DESP), which allows registering displacement fields with a high accuracy by tracing changes on the surface of the material under study and then comparing the specklograms recorded during uniaxial tension. The shape of the tensile curves σ(ε) undergoes a significant change with a decreasing temperature due to the γ-α'-phase transformation induced by plastic deformation. The processing of the deformation curves of the steel samples made it possible to distinguish the following stages of strain hardening, i.e. the stage of linear hardening and jerky flow stage. A comparative analysis of the design diagrams (with the introduction of additional parameters of the Ludwigson equation) and experimental diagrams of tension of steel 12Kh18N9T for different temperatures is carried out. The analysis of local strains distributions showed that at the stage of linear work hardening, a mobile system of plastic strain localization centers is observed. The temperature dependence of the parameters of plastic deformation localization at the stages of linear work hardening has been established. Unlike the linear hardening, the jerky flow possesses the propagation of single plastic strain fronts that occur one after another through the sample due to the γ-α' phase transition and the Portevin-Le Chatelier effect. It was found that at the jerky flow stage, which is the final stage before the destruction of the sample, the centers of deformation localization do not merge, leading to the neck formation.

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