Microstructural effects

One cannot emphasize too strongly the importance of direct, time-resolved experimental observation of microscale phenomena in establishing sound theories of microstructural effects under conditions of shock-wave compression. 

D.E. Grady, Microstructural Effects on Wave Propagation in Solids, Internat. J. Engrg. Sci. 22, 1181-1186(1984). 

Leslie, W.C., Microstructural Effects of High Strain Rate Deformation, in Metallurgical Effects at High Strain Rates (edited by Rohde, R.W., Butcher, B.M., Holland, J.R., and Karnes, C.H.), Plenum, New York, 1973, pp. 571-586. 

T. Hoshide. Simulation of microstructural effects on cracking behavior in biaxial fatigue. Mater Sci Res Int 5 119, 1997. 

Hemispherical shape of pit is often distorted by microstructural effects... 

Stoloff, N. S. and Duquette, D. J., Microstructural effects in the fatigue behaviour of metals and alloys , CRC Critical Reviews in Solid Slate Sciences, 4, 615-87 (1974)... 

Clearly, then, the chemical and physical properties of liquid interfaces represent a significant interdisciplinary research area for a broad range of investigators, such as those who have contributed to this book. The chapters are organized into three parts. The first deals with the chemical and physical structure of oil-water interfaces and membrane surfaces. Eighteen chapters present discussion of interfacial potentials, ion solvation, electrostatic instabilities in double layers, theory of adsorption, nonlinear optics, interfacial kinetics, microstructure effects, ultramicroelectrode techniques, catalysis, and extraction. 

Microstructure Effects on Transport in Reverse Microemulsions John Texter... 

Park S.S., Mackenzie J.D., Thickness and microstructure effects on alcohol sensing of tin oxide thin films, Thin Solid Films 1996 274 154-159. 

Strain hardening effect, 20 224 Straining efficiency, 77 340 Strain rate, 73 473 Strain recovery rate (Rr), in testing shape-memory polymers, 22 361 Strain sensors, 77 150, 151-152 Strain tensor, for noncentrosymmetry pont group crystals, 77 93-94 Strain versus time curve factors affecting, 73 473 material and microstructure effect on, 73 473-474... 

Current research efforts are concentrating on computationally efficient implementations of the energy equation within the MicroFlowS framework to allow realistic simulations of soot particle reaction in the porous structures. The next section shows a parallel line of development that started in Konstandopoulos and Kostoglou (2004), which tries to extend continuum models of soot oxidation to account for microstructural effects. 

Other low-temperature studies have been motivated by the desire to characterize and understand processes occurring in unusual media. For example, the use of liquid ammonia [8-10] and liquid sulfur dioxide [11-13] naturally requires reduced temperatures unless high pressures are used, as is done for electrochemistry in supercritical fluids [14]. Frozen media are interesting systems in terms of mass transport phenomena and microstructural effects. Examples include glasses of acetonitrile and acetone [15], frozen dimethyl sulfoxide solutions [16,17], and the solid electrolyte HC104 5.5 H20 [18-20]. 

We may summarize our discussion by noting that, in the parameter region given by Eqs. (1.18) we find universal behavior. Tt takes the form of crossover scaling laws, in limiting situations reducing to. simple povrer laws. Specific microstructure effects are contained in a few nonuniversal constants. 

Since, 3 = O( ), neglecting 0(0f2) in Eq, (8.31) is justified. Obviously the result (8,33) agrees with our general expectations since it neither depends on A nor on microstructure effects, which in Eq. (8.32) are contained in d. (Recall that this parameter collects contributions ai(e). a2(e), which in Sect. A 4.2 have been calculated by explicit evaluation of discrete segment summations.)... 

It has been observed that the concentrated solution viscosity decreases upon addition of TMEDA to solutions of poly(isoprenyl)lithium 93). This would be consistent with the process shown in Eq. (17) or (20) and not with Eqs, (18) or (19). The decrease in viscosity would be consistent with interaction of TMEDA to form an unassociated complex (Eq. (20)), but this does not seem to be in accord /with the stoichiometry observed by calorimetry. It is noteworthy that the break observed by calorimetry at R = 0.5 is consistent with the stoichiometric dependence of spectral, kinetic and microstructure effects 90). Again this shows that these kinetic effects are related to the stoichiometry of formation of base-organolithium adduct, i.e. that they are ground-state solvation effects. 

Electron microprobe analysis of concentration profiles across sections of the sintered samples revealed the existence of concentration gradients, the mullite content decreasing with increasing distance from the surface of the bodies [Marple Green, 1993], SEM examination also revealed a microstructural effect the alumina grain size tended to increase from the surface of the... 

B. Zhang et al Microstructural effects on high-cycle fatigue-crack initiation in A356.2 casting alloy. Metall. Matls. Trans. A 30, 2659—2666 (1999)... 

Often, it is not possible to obtain single crystals that are large enough to be worked with in a convenient manner. In those cases, physical properties must be measured on poly crystalline samples. There is always discrepancy, or disagreement, between measured physical properties of single crystals and polycrystals due to microstructural effects. Hence, physical properties measured from polycrystalline samples are sometimes considered less reliable from a reproducibility standpoint. 

The theoretical and experimental investigations of rupture and permeability of amphiphile bilayers are valuable also for the understanding of some microstructural effects in interfacial layers and phases of small volumes. The interpenetration of macroscopically measured quantities, e.g. r and W, by means of molecular statistical models seems to be most interesting and useful. As first attempts in this respect, a molecular statistical lattice model of such bilayers has been proposed [427] and a lattice model of such bilayers has been studied by means of Monte Carlo simulation by Chowdhury and Stauffer [429]. The results obtained have been compared with some experimental data presented in this Section. Clearly, the combination of macro and micro considerations is a promising way to obtain a deeper insight into the properties of matter and, especially, of interfacial layers and phases of small volumes. 

Concrete made with calcium aluminate cement at a properly low w/c ratio is highly resistant to sulphate solutions, sea water or dilute acid solutions with pH > 4, including natural waters in which CO2 is the only significant solute. Resistance may extend to pH 3 if the salt formed is of sufficiently low solubility. Midgley (M96) showed that, for fully converted material exposed to a sulphate ground water for 18 years, penetration with formation of a substituted ettringite was limited to a depth of 5 mm. These properties are consistent with Lea s (L6) view that the resistance is due to the formation of a protective coating of alumina gel, coupled with the absence of CH. No fundamental studies, e.g. on microstructural effects, appear to have been reported. 

Nikolov, A.D. and Wasan, D.T. "Layered Structures in Thin Liquid Films Micellar Interactions and Microstructure Effects on Film Stability," (in preparation). 

J.A. Poirier, G.E. Stoner, Microstructural effects on electronic oxygen reduction activity of nano-grained thin-film platinum in acid media. J. Electrochem. Soc. 1994, 141(2), 425 30. 

C. F. Chen and T. Y. Tien, High temperature mechanical properties of SiAION ceramics Microstructural effect. Ceram. Eng. and Sci Proc. 8 (7-8), 778-795 (1987). 

Here Cq = c(z = 0,t) and Dg is the effective diffusion coefficient (porosity and tortuosity effects are incorporated in Dg). If the upstream (high) pressure is constant and much larger than the downstream (low) pressure, the slope of the asymptote will correspond to the steady state and so it is possible to determine the diffusivity under both steady state and transient conditions from a single permeation experiment. With a narrow and unimodal pore size distribution both methods yield reasonable consistent values. Large discrepancies point to strong microstructural effects (bimodal broad distribution, many dead ends, many defects). 

Combination of several properties is becoming increasingly important in modem industry. One example may be taken from electronics, where in addition to mechanical properties and electric resistance, themial stability and conductivity are important requirements. It was estimated that the increase of temperature by 10°C reduces time to failure by the factor of two." A finite analysis model was developed which accounts for the following properties of filled composites microstructure, effect of particle shape, formation of conductive chains, effect of filler aspect ratio, and interfacial thermal resistance. The predictions of the model indicate the most... 

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