... ENVIRONMENT The model proposed is designed to balance the competing needs of simplicity and transparency on the one hand, and realism on the other It is a mass balance model that describes the fate ofmetals ... outcome ofthe model, as shown in Table 3.2 These are the ecotoxicity and bioaccumulation, the speciation and partitioning reactions among water, sediment, and soil, andthe role ofthe biota ... 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, substances...
... role of misfit between the crystal lattice parameters ofthe matrix andofthe hardening phase The subject ofthe last chapter is the peculiarities ofthe strain behavior of refractory metals ... place in the atomic crystal lattice ofmetalsandalloys However, if we want to understand the nature of these processes and to be able to use them in practice we should try to investigate them directly ... aeroplanes, and aerospace vehicles depends directly on the ability of their parts and units to withstand changes in shape On the other hand, a significant mobility of crystal lattice defects andof atoms...
... 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 ... amplitudes and diffusion parameters The smaller the amplitudes ofthe atomic oscillations the smaller is the diffusion mobility ofthe atoms andthe greater the resistance to applied stresses Therefore ... frame ofthe chamber in order to provide rotation ofthe specimen around the axis ofthe goniometer during its exposure to X-rays The mechanism must be able to create a load ofthe order of thousands...
... values of D and η are somewhat distinct There is a distribution in the size of these values, however, one may consider the mean values The accuracy ofthe method is of concern We have used the t-distribution ... 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 ... of face-centered metalsThe presence of a screw component in the boundary structure is the third distinctive feature ofthe structure ofthe high-temperature deformed metalsThe fourth peculiarity...
... are cosines of angles between the respective axes Averaging the product ofthe cosines over all orientations ofthe new coordinate system and finding the average value ofthe function of two variables ... Comparison ofthe temperature dependence ofthe creep rates ε under stress of 80 MPa (a) andofthe ˙ mean-square atomic amplitudes (b) for nickel-based alloysThe composition ofalloys (at.%): ... changing the signs ofthe vectors ξ3 and ξ4 During parallel slip of dislocations ξ1 and ξ2 the displacement ofthe crystal part takes place in the plane which is determined by the vectors ξ1 × V1 and...
... the factor n appears before the second term on the right-hand side of Eq (4.27) In Fig 4.17 the calculated curves ofthe influence of temperature and stress on the Γ value are shown for two metals ... dislocation to the sub-boundary Thus, the dislocation is pinned with pinning point density 1/λ and is emitted by means of thermal activation According to the theory ofthe rates of reactions [25] the dislocation ... two metalsThe probability of dislocation emission from the sub-boundary is strongly affected by the temperature andthe number of dislocations in the slip plane Fig 4.17 The number of thermal activations...
... nuclear reactors and landing apparatus The structure ofthe majority of nickel-based superalloys consists of a matrix i.e ofthe γ phase and particles ofthe hardening γ phase The γ phase is a ... ofthe positive terms on the right-hand side of Eq (5.3) is equal to the sum ofthe absolute values ofthe negative terms The velocity, V , ofthe mobile dislocations decreases gradually At the ... vertices ofthe cubic cell and form the sublattice A Atoms of nickel are located at the centers ofthe faces and form the sublattice B In fact the phase is not strictly stoichiometric, there may...
... the average length of segment, which is activated l inside the particle The displacement ofthe segment is equal to the Burgers vector length |b| On the basis ofthe theory ofthe activated reactions ... 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 ... 6.2 the values of l andthe average particle dimensions 2¯ are listed The lengths ofthe activated dislocation segments are one order less than the average particle sizes Values ofthe ratio of...
... amplitudes ofthe atom vibrations in the hardening phase the higher the creep strength of a superalloy Methods of prediction ofthe properties of new superalloys are being developed on the basis of integrated ... phase At the stage ofthe tertiary creep the shape ofthe particles becomes irregular as the coarsening of precipitates takes place The experimental dependences between the logarithm ofthe minimum ... compared the mean-square atomic amplitudes in strengthening phases of superalloys with the rate ofthe steady-state creep ε ofthe same ˙ alloysThe superalloy EI437B with u2 = 460 pm2 at 1023K has the...
... affect the physical mechanism of strain ofthe investigated superalloys There exists a competition between the Orowan mechanism of bowing ofthe dislocations between the γ particles andthe cutting ... structure ofthe cast single crystal may be considered as two interdependent systems Therefore the properties of phases influence the generation and motion of dislocations as the phase boundaries In the ... the size ofthe γ particles promotes glide of a/2 < 110 > dislocations within the γ matrix and leads to a decrease in the primary creep amplitude However, the excessive increase in the size of...
... be important in the theory of strength and plasticity [18, 20, 21] Let us recall the main theses ofthe theory of dislocations A crystal lattice is not ideal The arrangement of atoms differs ... movement ofthe dislocation through the crystal occurs and an extra-plane appears above the slip plane The shift ofthe upper half ofthe crystal takes place after the dislocation emerges from the ... the magnitude ofthe Burgers vector andthe shear modulus ofthe material, µ, as Eel ≈ µb2 The atoms nearest to the dislocation core are displaced most from their equilibrium positions and therefore...
... the plasticity and creep ofmetalsand ceramic, Dartmouth College, USA and Cambridge University, UK, Ch 5, 2003 Web version 27 I Kelareva, personal communication 28 V Levitin, The evolution of ... in 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 ... 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...
... in the apical membranes of gill and other epithelia that can take up both Ca2+ and Cd2+ (Verbost et al 1987) because of similarities in their charge and ionic radius Another important aspect of ... between these systems is the nature ofthe gill and gut environment The gill environment reflects the composition ofthe external solution to a certain extent although gradients in proton and other ... membranes ofthe epithelial cells by endocytosis and further metabolic processing The intestine is also the site of small organic molecule uptake Metals may bind to these molecules and inadvertently...
... 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 ... input to the UWM, and (3) providing an interim solution to the use of aquatic toxicity data in metal categorization, independent ofand in advance ofthe UWM 5.2 DATA ACCEPTABILITY The goal of characterization ... has been adopted as the speciation component ofthe BLM The current use of WHAM (Tipping 1994) in the BLM construct, however, does not preclude the future use of other types of speciation models,...
... climate and land use 6.3.3 AGING OFMETALS IN SOIL Persistence of total metals in soil and persistence of metal bioavailability and solubility are not the same In the latter case, the process ... affecting the mass balance ofmetals in soils are the anthropogenic and natural inputs andthe outputs via leaching to groundwater and removal through surface erosion and crop harvesting The elimination ... ratio ofthe metal concentration in plants to the concentration in soil, R is net drainage of water out ofthe soil (m3 ha–1 y–1), ρ is the bulk density ofthe soil (tondw m–3 or kgdw L–1), and...
... depend upon the composition, the quality andthe grain size ofthe deposit These in their turn depend on the parent and filler metal compositions, the amount of dilution, the quality ofthe welding ... ions andthe cloud of mobile, negatively charged electrons that binds the metal together These atomic scale events give metals their high thermal and 12 The welding of aluminium and its alloys ... geometry ofthe phases depends on their relative amounts, whether the minor phase is dispersed within the grains or is present on the grain boundaries andthe size and shape ofthe phases The phases...
... access to the array and, if other clients had already referenced the data ofthe array, the physical memory cache ofthe array would be directly accessible to the client with no further message ... 5.5 Fault Handling The Mach page fault handler is the hub ofthe Mach virtual memory system The kernel fault handler is called when the hardware tries to reference a page for which there no valid ... vm_allocate_with_pager) or receipt of data in an IPC message In the first case, the source ofthe data is considered trusted (either the default pager, or a data manager known to the requestor) Use ofthe data received...
... worked in the communications sector Twenty years later, though the number of men remained unchanged, the number of women rose to 550 000 A similar situation was seen in the wholesale and retail ... 450 000 by 1995 The number of men grew only marginally from 425 000 to 480 000 over the same period In defence, the number of men declined from 225 000 to 200 000, while the number of women rose ... answer: The two decades between 1975 and 1995 brought significant changes in the representation of women in Freedonia's work force, according to the graphs In 1975, for example, some 300 000 men and...
... evidence is the lack of rigour and generalisability Furthermore, the magnitude ofthe effect ofthe MET may be influenced by institution-specific administrative features and policies Buist and coworkers ... of centres Before -and- after studies lack rigour and generalisability they are In the words ofthe slogan ofthe American Society of Critical Care Medicine, we need to deliver the ‘right care, ... lack of statistical power due to the large variance in outcome incidence and wide standard deviation andthe lower-than-expected incidence ofthe outcome measures under investigation Given the...