Coherency strain

From room temperature up to 150 °C the coherent Cu-rich Guinier-Preston zones I (GPI phase) form they are only one to two 001 layers thick and have a highly strained, coherent phase boundary with the cr-Al matrix phase. 

Shearography monitors the speckular 2D interference pattern of an unpolished surface illuminated by a coherent light source, and is therefore a metliod that lends itself to the testing of industrial materials. Small surface, or near-surface defects may produce localised strain on... 

If this is subjected to the "Bain strain" it becomes an undistorted b.c.c. cell. This atomic "switching" involves the least shuffling of atoms. As it stands the new lattice is not coherent with the old one. But we can get coherency by rotating the b.c.c. lattice planes as well (Fig. 8.8). 

The coherency strains around the GP zones and 0" precipitates generate stresses that heip prevent disiocation movement. The GP zones give the iarger hardening effect (Fig. 10.7). 

Dodson BW. 1987. Atomistic study of stmctural instabilities in coherently strained Si-like layers. Phys Rev B 35 5558-5562. 

Maughan S.M., Kee H.H., Newson T.P., Simultaneous distributed fibre temperature and strain sensor using microwave coherent detection of spontaneous Brillouin backscatter, Meas. Sci. Technol. 2001 12 834-842. 

Coherency strains, 13 501 Coherent anti-Stokes Raman scattering (CARS), 21 328 Cohesive energy, 23 90 Coho salmon, common and scientific names, 3 187t... 

If the specimen crystal is curved, there will be a range of positions where the diffraction conditions are satisfied even for a plane wave. The rocking curve is broadened. It is simple to reduce the effect of curvature by reducing the collimator aperture. For semiconductor crystals it is good practice never to mn rocking curves with a collimator size above 1 mm, and 0.5 mm is preferable. Curved specimens are common if a mismatched epilayer forms coherently on a substrate, then the substrate will bow to reduce the elastic strain. The effect is geometric and independent of the diffraction geometiy. Table 2.1 illustrates this effect. 

Calculate the strains and that would be applied if the lattice parameters in the interface plane of the layer were forced to conform to the substrate (full coherent epitaxy). Multiply these by (1-i ) where R is the (fractional) relaxation of the layer. (See the discussion of measurement of relaxation in Chapters.)... 

Figure 3.16 Solvus and spinodal decomposition fields as a function of elastic strain, (a) Strain-free or chemical solvus (b) strain-free spinodal (c) coherent solvus (d) coherent spinodal. From Ganguly and Saxena (1992). Reprinted with permission of Springer-Verlag, New York.

The compositional relations of the sodic and potassic phases in perthites depend on whether the phases are coherent or not. If the perthitic phases are non-coherent (or if the rock consists of separate grains of sodic and potassic feldspar) their equihbrium compositions are given by the strain-free solvus. This is the solvus which has been studied extensively in the past. These sentences. 

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