... mechanisms ofthe high- temperature deformation of pure metalsand solid solutions are worked out on the basis ofthe obtained data The quantitative model of creep is considered and validated Equations ... Peculiarities of High- temperature Deformation 40 Summary 41 Physical Mechanism of Strain atHighTemperatures Physical Model and Theory 43 Velocity of Dislocations 45 Dislocation Density 49 Rate ofthe ... Effect of Orientation on Properties 111 Deformation at Lower Temperatures 116 Deformation at Higher Temperatures 124 On the Composition of Superalloys 129 Rafting 130 Effect of Composition and Temperature...
... amplitudes ofthe atomic oscillations the smaller is the diffusion mobility ofthe atoms andthe greater the resistance to applied stresses Therefore measurements of amplitudes of atomic oscillations ... motion of atoms has a great influence on the interference pattern The intensity ofthe scattering ofthe X-rays by a group of atoms subjected to independent heat vibrations is weakened by the factor ... angle ω ofthe crystal rotation andthe two angles, 2θ and ψ, ofthe detector motion Angles ω and 2θ are measured in the equatorial (horizontal) plane ofthe goniometer and angle ψ in the meridianal...
... features of strain (creep) athightemperaturesand it turns out that these features are caused by a certain physical mechanism The first distinctive feature is the simultaneous formation of ... other The following conclusion look obvious: it is the process of substructure formation that is the cause ofthe decrease in the plastic strain rate The subgrain dimensions are ofthe order of ... Fig 3.14 and in other areas marked with the letter j These kinks at mobile dislocations turn out to be of great importance for our understanding ofthe physical mechanism ofthe steady-state creep...
... Physical Mechanism of Strain atHighTemperatures where ρm is the rate ofthe density increase due to the dislocation multipli˙d cation, ρm is the rate ofthe density change on account ofthe sub-boundary ... 4.10) The amplitudes of atomic vibrations correlate with one ofthe main characteristics ofthe high- temperature strength – the rate ofthe stationary creep One can see in Fig 4.10 that the creep ... 4.4 Rate ofthe Steady-State Creep state strain rates atthe test temperatures 673, 873, and 1023K When the temperature is increased to 1173K the theoretical model fails Fig 4.7 The steady-state...
... Most heat-resistant metals, steels andalloys operate attemperatures between 0.40 and 0.75 Tm The area of temperature and stress where the proposed mechanism of hightemperature deformation takes ... amplitude of atomic vibrations athightemperaturesThe developed theory is valid within certain limits ofthe temperature and applied stress When the temperature is relatively low, the dislocation ... measured The quantitative evaluation ofthe strain rate was out ofthe question at that time, of course As a matter of fact, the adjacent jogs of opposite signs slip along the dislocation line...
... generation andofthe dislocation annihilation (immobilization) are equal The sum ofthe positive terms on the right-hand side of Eq (5.3) is equal to the sum ofthe absolute values ofthe negative ... aluminum are placed atthe vertices ofthe cubic cell and form the sublattice A Atoms of nickel are located atthe centers ofthe faces and form the sublattice B In fact the phase is not strictly ... deformation the rates ofthe dislocation generation and annihilation seem to be equal andthe parameters λ and D are constant Thus, we should solve the system of equations to calculate the density...
... heat-induced atomic vibrations andthe forces of interatomic bonds in the crystal lattice ofthe hardening γ phase It seems natural that the greater the vibration amplitude the greater ... diagonal [10¯ atoms of 1] aluminum and nickel are altered Atoms of Ni that are denoted as andof Al that are denoted as are located in the first slip plane Atoms of Ni andof Al are located in the second ... 2l The value of ∆U in Eq (6.8) is close to the activation energy of generation and migration of vacancies in the ordered phase The sum of these values is known to be the energy activation of...
... significantly in the aluminum sublattice We have compared the mean-square atomic amplitudes in strengthening phases of superalloys with the rate ofthe steady-state creep ε ofthe same ˙ alloysThe superalloy ... 50–80 pm2 at 1023K The smaller the mean-square amplitudes ofthe atom vibrations in the hardening phase the higher the creep strength of a superalloy Methods of prediction ofthe properties of new ... 110 High- temperature Deformation of Superalloys In a phase of type B3 A (Ni3 Al) Ti atoms occupy places in sublattice A Cr, Fe and Co atoms are located mostly in sublattice B Atoms of Mo, Nb and...
... Deformation at Lower Temperatures Fig 7.7 The orientation ofthe CMSX-4 superalloy specimens within the stereographic triangle The effect of misorientation on the behavior of specimens at lower temperatures ... temperatures is very strong The authors noted that the magnitude ofthe steady-state creep rate correlates with the maximum rate in the primary creep stage The further from the < 001 > orientation ... in terminating the primary creep Thus, the primary creep at lower temperatures starts with the propagation of a/2 < 110 > dislocations through the γ channels The sources of these dislocations supposedly...
... a coating The minimum strain rate of niobium and molybdenum is dependent exponentially on the applied stress athightemperaturesThe mean value ofthe activation energy ofthe high- temperature ... Dislocations in the Crystal Lattice The concept of dislocations is known to be important in the theory of strength and plasticity [18, 20, 21] Let us recall the main theses ofthe theory of dislocations ... crystal lattice is not ideal The arrangement of atoms differs from a regular order This is the immediate cause ofthe great discrepancy between the theoretical strength of materials andthe measured...
... nickel-tungsten alloys, J Jpn Inst Met 1964, 28 (4), 177–200 24 V.K Pishchak, The substructure evolutions andthe high- temperature creep mechanisms ofmetals with face- and body-centered crystal lattices, ... Creep deformation of gamma-primed hardened nickel-based alloys, Jernkontor Ann 1971, (3), 125–133 36 G.A Webster, B.J Piercey, An interpretation ofthe effects of stress and temperature on the creep ... 40 O.V Rubel, Regulation of selection of a crystallographic orientation ofthe turbine blades manufactured by the directional solidification method, PhD thesis, Zaporozhye State Technical University,...
... criteria in the different regulatory arenas in Canada, Europe, andthe United States Additional presentations highlighted the state ofthe science regarding the interpretation of PBT for metals These ... placed at possible risk if the substance enters the environment, with the degree (probability) of risk related to the hazardous nature ofthe substance andthe amount of exposure that occurs Therefore, ... analyses ofthe degree of partitioning of a variety ofmetals have been performed to provide insight concerning their persistence in the water column andthe rate of delivery of sorbed metal to aquatic...
... Primer-R: AGCATCCTGGAGAGATCAGCAT NM213861 IFN-γ Primer-F: AGCTCTGGGAAACTGAATGACTTC MGB Probe: AATTCCGGTAGATAATCT Primer-R: TGATGAGTTCACTGATGGCTTTG X53085 TNF-α Primer-F:GATCATCGTCTCAAACCTCAGATAAG MGB ... Quantification of regulatory and inflammatory cytokine mRNA levels in the spleen of pigs Vertical bars represent the mean ± SE of these results for different treatment (n = 12) It is possible that ... thickening and dilatation in liver, D; Lymphocyte necrosis and deletion of spleen, F; Local necrosis and lymphocyte depletion of lymph node, H; Glomerulus dilatation andthe Bowman's capsule full of...
... multiplying the uptake rate constant by the metal water concentration andthe elimination rate by multiplying the body metal concentration by the elimination rate constant Under steady-state conditions, ... less than K atthe range of metal concentrations investigated, andthe above equation reduces to CTB = (max/K) · CW + CBk (4.2) andthe ratio max/K is estimated directly The ratio of max/K is ... that essential functions are impaired (e.g., inhibition of enzymes or transporters by binding ofmetals in the catalytic centre ofthe molecule) When the rate of metal uptake exceeds the rate of...
... 1999) The ultimate objective is to assess the toxicity ofthe metal species rather than that ofthe original metal substance 5.2.1 DATA EVALUATION AND SPECIES SELECTION CRITERIA Toxicity data ofthe ... species, and (2) the toxicity of these species, rather than (3) the toxicity ofthe original metal substance There is no doubt that characteristics such as solubility and transformation (and their ... independent ofand in advance ofthe UWM 5.2 DATA ACCEPTABILITY The goal of characterization is often to evaluate and compare the relative hazard/risk of different compounds, whether inorganic...
... increasing incubation temperature The soil and environmental factors governing attenuation rates were: soil pH, organic matter content, incubation time, and temperature The attenuation of Cu lability ... and invertebrates (the ratio ofthe concentration in biota to the concentration in soil) can then be compared to the toxicity/soil ratio If the former is much smaller than the latter, the metal ... calculated relative to Cd (Figure 6.5) Further, at least soils should be selected for the tests, one that accentuates the bioavailability of cationic metals (pH to 5.5) andthe other that maximizes...
... unless they regard the materials they are taught as worth learning Therefore, the task ofthe teachers is to find out their students‟ goal andthe topics 48 they want to learn and build these in the ... description of teaching and learning situation atthe HCIE including the English course, the first year students andthe teachers atthe HCIE It also includes the main part ofthe study Basing on the ... on one hand and develop their English for Economics on the other hand with the hope that they can use English as a useful tool in their career 30 2.1.3 Description ofthe teachers atthe HCIE...
... words that begin with vowels Read after the teacher Put the book on the top ofthe shelf He taught us a lot about language Breathe in and breathe out Sit atthe back ofthe room He made a lot of money ... consists of three main parts: Part I is the introduction ofthe thesis in which we present the reasons for choosing the subject, the aims, the scope, the methods andthe design ofthe thesis Part ... Table of Contents Page Part I: Introduction The Reasons for Choosing the Study The Aims ofthe Study The Scope ofthe Study The Methods ofthe Study 5 The Design...