the sulfidation of metals and alloys

... 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 of metals ... outcome of the model, as shown in Table 3.2 These are the ecotoxicity and bioaccumulation, the speciation and partitioning reactions among water, sediment, and soil, and the role of the biota ... possible risk if the substance enters the environment, with the degree (probability) of risk related to the hazardous nature of the substance and the amount of exposure that occurs Therefore, substances...

Ngày tải lên: 16/03/2014, 11:45

... role of misfit between the crystal lattice parameters of the matrix and of the hardening phase The subject of the last chapter is the peculiarities of the strain behavior of refractory metals ... place in the atomic crystal lattice of metals and alloys 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 and of atoms...

Ngày tải lên: 10/08/2014, 12:21

... angle ω of the crystal rotation and the two angles, 2θ and ψ, of the detector motion Angles ω and 2θ are measured in the equatorial (horizontal) plane of the goniometer and angle ψ in the meridianal ... amplitudes and diffusion parameters The smaller the amplitudes of the atomic oscillations the smaller is the diffusion mobility of the atoms and the greater the resistance to applied stresses Therefore ... frame of the chamber in order to provide rotation of the specimen around the axis of the goniometer during its exposure to X-rays The mechanism must be able to create a load of the order of thousands...

Ngày tải lên: 10/08/2014, 12:21

... 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 of the 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 of the decrease in the plastic strain rate The subgrain dimensions are of the order of ... of face-centered metals The presence of a screw component in the boundary structure is the third distinctive feature of the structure of the high-temperature deformed metals The fourth peculiarity...

Ngày tải lên: 10/08/2014, 12:21

... are cosines of angles between the respective axes Averaging the product of the cosines over all orientations of the new coordinate system and finding the average value of the function of two variables ... Comparison of the temperature dependence of the creep rates ε under stress of 80 MPa (a) and of the ˙ mean-square atomic amplitudes (b) for nickel-based alloys The composition of alloys (at.%): ... changing the signs of the vectors ξ3 and ξ4 During parallel slip of dislocations ξ1 and ξ2 the displacement of the crystal part takes place in the plane which is determined by the vectors ξ1 × V1 and...

Ngày tải lên: 10/08/2014, 12:21

... the factor n appears before the second term on the right-hand side of Eq (4.27) In Fig 4.17 the calculated curves of the 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 of the rates of reactions [25] the dislocation ... two metals The probability of dislocation emission from the sub-boundary is strongly affected by the temperature and the number of dislocations in the slip plane Fig 4.17 The number of thermal activations...

Ngày tải lên: 10/08/2014, 12:21

... nuclear reactors and landing apparatus The structure of the majority of nickel-based superalloys consists of a matrix i.e of the γ phase and particles of the hardening γ phase The γ phase is a ... of the positive terms on the right-hand side of Eq (5.3) is equal to the sum of the absolute values of the negative terms The velocity, V , of the mobile dislocations decreases gradually At the ... vertices of the cubic cell and form the sublattice A Atoms of nickel are located at the centers of the faces and form the sublattice B In fact the phase is not strictly stoichiometric, there may...

Ngày tải lên: 10/08/2014, 12:21

... the average length of segment, which is activated l inside the particle The displacement of the segment is equal to the Burgers vector length |b| On the basis of the theory of the 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 and the average particle dimensions 2¯ are listed The lengths of the activated dislocation segments are one order less than the average particle sizes Values of the ratio of...

Ngày tải lên: 10/08/2014, 12:21

... amplitudes of the atom vibrations in the hardening phase the higher the creep strength of a superalloy Methods of prediction of the properties of new superalloys are being developed on the basis of integrated ... phase At the stage of the tertiary creep the shape of the particles becomes irregular as the coarsening of precipitates takes place The experimental dependences between the logarithm of the minimum ... compared the mean-square atomic amplitudes in strengthening phases of superalloys with the rate of the steady-state creep ε of the same ˙ alloys The superalloy EI437B with u2 = 460 pm2 at 1023K has the...

Ngày tải lên: 10/08/2014, 12:21

... affect the physical mechanism of strain of the investigated superalloys There exists a competition between the Orowan mechanism of bowing of the dislocations between the γ particles and the cutting ... structure of the 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 of the 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...

Ngày tải lên: 10/08/2014, 12:21

... be important in the theory of strength and plasticity [18, 20, 21] Let us recall the main theses of the theory of dislocations A crystal lattice is not ideal The arrangement of atoms differs ... movement of the dislocation through the crystal occurs and an extra-plane appears above the slip plane The shift of the upper half of the crystal takes place after the dislocation emerges from the ... the magnitude of the Burgers vector and the shear modulus of the material, µ, as Eel ≈ µb2 The atoms nearest to the dislocation core are displaced most from their equilibrium positions and therefore...

Ngày tải lên: 10/08/2014, 12:21

... the plasticity and creep of metals and 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 and the high-temperature creep mechanisms of metals 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 of the effects of stress and temperature on the creep...

Ngày tải lên: 10/08/2014, 12:21

... in-depth discussion of the potential to assess bioavailability of metals to fish and invertebrates (Bergman and Dorward-King 1996) and which led to the development of the Biotic Ligand Model (BLM) ... presentations highlighted the state of the science regarding the interpretation of PBT for metals These presentations provided the © 2007 by the Society of Environmental Toxicology and Chemistry (SETAC) ... possible risk if the substance enters the environment, with the degree (probability) of risk related to the hazardous nature of the substance and the amount of exposure that occurs Therefore, substances...

Ngày tải lên: 12/08/2014, 04:22

... 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 of the gill and gut environment The gill environment reflects the composition of the external solution to a certain extent although gradients in proton and other ... membranes of the 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...

Ngày tải lên: 12/08/2014, 04:22

... species, and (2) the toxicity of these species, rather than (3) the toxicity of the 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 of and in advance of the UWM 5.2 DATA ACCEPTABILITY The goal of characterization ... has been adopted as the speciation component of the 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,...

Ngày tải lên: 12/08/2014, 04:22

... climate and land use 6.3.3 AGING OF METALS 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 of metals in soils are the anthropogenic and natural inputs and the outputs via leaching to groundwater and removal through surface erosion and crop harvesting The elimination ... ratio of the metal concentration in plants to the concentration in soil, R is net drainage of water out of the soil (m3 ha–1 y–1), ρ is the bulk density of the soil (tondw m–3 or kgdw L–1), and...

Ngày tải lên: 12/08/2014, 04:22

... depend upon the composition, the quality and the grain size of the deposit These in their turn depend on the parent and filler metal compositions, the amount of dilution, the quality of the welding ... ions and the 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 of the phases depends on their relative amounts, whether the minor phase is dispersed within the grains or is present on the grain boundaries and the size and shape of the phases The phases...

Ngày tải lên: 12/03/2014, 17:32

... access to the array and, if other clients had already referenced the data of the array, the physical memory cache of the array would be directly accessible to the client with no further message ... 5.5 Fault Handling The Mach page fault handler is the hub of the 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 of the data is considered trusted (either the default pager, or a data manager known to the requestor) Use of the data received...

Ngày tải lên: 12/09/2012, 15:05

... 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...

Ngày tải lên: 04/10/2012, 10:02

... evidence is the lack of rigour and generalisability Furthermore, the magnitude of the effect of the 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 of the slogan of the 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 and the lower-than-expected incidence of the outcome measures under investigation Given the...

Ngày tải lên: 25/10/2012, 10:35