Poly crystalline materials

For a typical poly crystalline material the concentration profile is divided into three segments. Near the original surface the tracer distribution will be characteristic of volume diffusion and show a typical bell shape. The average tracer concentration... 

B. Burton. Diffusional Creep of Poly crystalline Materials. Diffusion and Defect Monograph Series, No. 5. Trans Tech Publications, Bay Village, OH, 1977. 

Removal of contamination by ion bombardment with inert gas ions, followed by annealing. This method can be applied to either single or poly-crystalline materials and has been found to be effective for the compound indium antimonide having a melting point of 525°C as well as for more refractory materials, ft has also been found to be effective in removing a monolayer of carbon from nickel and silicon crystals. 

The most obvious application of the Jeener echo is to measure T by plotting echo amplitude vs. time spent in a state of dipolar order. If the system under study is homogeneously broadened, then the location on the echo where the amplitude is measured, provided it is chosen consistently, is immaterial for the measurement of T - In an inhomogeneously broadened system, such as a poly crystalline material, the Jeener echo may be a superposition of Jeener echoes with different shapes and different T- s. If so, it may matter where the echo amplitude is sampled. The most obvious test is to plot relaxation curves from different parts of the echo to determine whether the echo is relaxing uniformly. For a crystalline material, one expects that the dipolar relaxation time T p will be independent of the crystal orientation in the external field because the state of dipolar order is independent of this external field. 

Fig. I (a) Diffraction from an oriented single crystal, (b) from a collection of four crystals at different orientations with respect to the incident beam, and (c) from a poly crystalline material. 20 increases from the film center to the edge.

Abstract. The crystallographic texture is defined as the relative organization of the grains in an anisotropic solid which infiuences frequently its physics and mechanical properties. This is the case of majority of poly crystalline materials rocks, ceramics, metals, polymers, etc. 

The Orientation Density Function (ODF) is defined and the calculations for the general knowledge about texture analysis in poly crystalline materials. The difference between local and global textures allows to determine the ODF more precisely and to describe the grains orientation relationships. 

An expression for creep may be given in terms of shear-strain rate and shear stress, when both lattice- and grain-boundary diffusion are involved in the deformation. For most poly crystalline materials, diffusion in grain boundaries is more rapid than in the lattice. 

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