Microstructural relations

While the various strategies described above have proven promising, SOFC electrodes remain largely empirically understood and far from optimized and suffer from numerous short- and long-term degradation problems. Reported performances vary tremendously with many unknown variables at work and limited understanding as to how materials properties and microstructure relate to performance and long-term stability. ... 

So far we have considered how the microstructure relates to the physical properties of ice cream. The sensory properties, however, are determined not only by the microstructure, but also by how it breaks... 

Hills, L.M., Clinker Microstructure Related to Grindability, RP272, Portland Cement Association, Skokie, Illinois, 1996,22 pp. 

S.B. Fisher, J.E. Harbottle and N. Aldridge, Microstructure related to irradiation hardening in pressure vessel steels, Dimensional Stability and Mechanical Behaviour of Irradiated Metals and Alloys, British Nuclear Energy Society, London, 1984, vol. 2, pp. 87-91. 

Kargei-Kocsis J and Friedrich K (1993) Microstructure-related fracture toughness and fatigue crack growth behavior in toughened, anhydride-cured epoxy resins, Compos Sci Technol 48 263-272. 

L. J. Dijkstra, Relation of Magnetic Properties to Microstructure, Relation of Properties to Microstructure,ASM, 209-232 (1954). 

The oxide formed on a metal during high-temperature oxidation is usually considered to be polycrystalline. This introduces the possibility that the detailed mechanism of the oxidation may be sensitive to the microstructure ( ). In this work the grain size of Zr02 formed on Zr has been determined and the observed microstructure related to the diffusion mechanism through the oxide and to the crystal structure. 

Other elements of the microstructure relate to the shape and distribution of the phases. In this respect, the cementite phase has distinctly different shapes and arrangements in the pearlite and spheroidite microstructures (Figures 10.15 and 10.19). Alloys containing pear-litic microstructmes have greater strength and hardness than do those with spheroidite. This is demonstrated in Figure 10.30a, which compares the hardness as a function of the... 

This book has been written as a second-level course for engineering students. It provides a concise introduction to the microstructures and processing of materials (metals, ceramics, polymers and composites) and shows how these are related to the properties required in engineering design. It is designed to follow on from our first-level text on the properties and applications of engineering materials," but it is completely self-contained and can be used by itself. 

In image mode, the post-specimen lenses are set to examine the information in the transmitted signal at the image plane of the objective lens. Here, the scattered electron waves finally recombine, forming an image with recognizable details related to the sample microstructure (or atomic structure). 

There are many applications for diamonds and related materials, e.g., diamondlike carbon films, and there are potential applications for Fullerenes and carbon nanotubes that have not yet been realised. However, the great majority of engineering carbons, including most of those described in this book, have graphitic microstructures or disordered graphitic microstructures. Also, most engineering carbon materials are derived firom organic precursors by heat-treatment in inert atmospheres (carbonisation). A selection of technically-... 

The study of microstructures in relation to important properties of metals and alloys, especially mechanical properties, continues apaee. A good overview of eurrent concerns can be found in a multiauthor volume published in Germany (Anon. 1981), and many chapters in my own book on physieal metallurgy (Cahn 1965) are devoted to the same issues. 

The first detailed book to describe the practice and theory of stereology was assembled by two Americans, DeHoff and Rhines (1968) both these men were famous practitioners in their day. There has been a steady stream of books since then a fine, concise and very clear overview is that by Exner (1996). In the last few years, a specialised form of microstructural analysis, entirely dependent on computerised image analysis, has emerged - fractal analysis, a form of measurement of roughness in two or three dimensions. Most of the voluminous literature of fractals, initiated by a mathematician, Benoit Mandelbrot at IBM, is irrelevant to materials science, but there is a sub-parepisteme of fractal analysis which relates the fractal dimension to fracture toughness one example of this has been analysed, together with an explanation of the meaning of fractal dimension , by Cahn (1989). 

The type of manufacturing process, reaction conditions, and catalyst are the controlling factors for the molecular structure of the polymers [4-8]. The molecular features govern the melt processability and microstructure of the solids. The formation of the microstructure is also affected by the melt-processing conditions set for shaping the polymeric resin [9]. The ultimate properties are, thus, directly related to the microstructural features of the polymeric solid. 

Most materials, be they natural or synthetic, have limited utility. However, technical ingenuity has increased the utility of these materials beyond anyone s wildest imagination. The enormous range of steel that can be produced by adding carbon or other elements to give it the required balance of properties, such as strength and hardness, related to changes in their microstructure [1-3] is just one example. 

PET fibers in final form are semi-crystalline polymeric objects of an axial orientation of structural elements, characterized by the rotational symmetry of their location in relation to the geometrical axis of the fiber. The semi-crystalline character manifests itself in the occurrence of three qualitatively different polymeric phases crystalline phase, intermediate phase (the so-called mes-ophase), and amorphous phase. When considering the fine structure, attention should be paid to its three fundamental aspects morphological structure, in other words, super- or suprastructure microstructure and preferred orientation. 

Some of the above discussed precursor phenomena are also observed prior to diffusion driven phase transformations. A typical example are the conventional EM tweed images obtained in the tetragonal parent phase in high Tc superconductors and other ceramics. In a recent survey by Putnis St e of such observations it was concluded that in these cases the tweed contrast resulted from underlying microstructures fomied by symmetry changes driven by cation ordering. These symmetry changes yield a fine patchwork of twin related domains which coarsen when the transfomiation proceeds. However, in view of the diffusion driven character of the latter examples, these cases should be clearly separated from those in the field of the martensites. 

The primary question is the rate at which the mobile guest species can be added to, or deleted from, the host microstructure. In many situations the critical problem is the transport within a particular phase under the influence of gradients in chemical composition, rather than kinetic phenomena at the electrolyte/electrode interface. In this case, the governing parameter is the chemical diffusion coefficient of the mobile species, which relates to transport in a chemical concentration gradient. 

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