Effect Of Domain Size Research Articles

Analysis of coherence, strain, thermal vibration and preferred orientation in carbons by X-Ray diffraction

In ideal graphitic layers the inter-atomic (or inter-unit cell) distances l and the number of atoms (or unit cells) n( l) at a distance from any atom (or unit cell) chosen as origin may be represented by sets l and n( l) which define the structure. In the defective lattice theory presented here the structure of diffusely scattering (the so-called amorphous) carbons are likewise defined by the two sets, however n( l)'s are modified by a probability (coherence probability) function g( l) and l' s are modified for dispersion (strain effects). It is shown that the coherence probability function can be determined from the atomic radial distribution curves without a priori knowledge of distortion and temperature diffuse scattering. Analytical expressions have been developed that permit analysis of distortion and temperature diffuse scattering from the observed profiles of the diffuse peaks and from the atomic radial distribution functions. In analyzing the distortion, Gauss', Gauchy's and Laplace's distributions are considered. It is demonstrated that distortion could be responsible for the diffuseness of the diffraction profiles of carbons to a greater extent than the coherence probability, the so-called domain or particle size effect. It is also shown that the integrated intensities, I( φ), of the (00 l) reflections of anisotropic, e.g. pyrolytic, carbons are related to the angle φ that the diffraction vector makes with the pole of the sample by I( φ) = K exp (− p 2 sin 2 φ) in which K is the proportionality constant and p is the characteristic parameter of the sample. The equation has a reasonably sound physical basis and has been found to be applicable to samples having a wide range of preferred orientations.

The effects of fillers, crosslinking agents, and domain size on the physical properties of PE–PCV blends

AbstractBlends of polyethylene and poly(vinyl chloride) were prepared on a Brabender Plasticorder, and attempts were made to improve the very inferior physical properties of the product. The blends were found to have domain structures, and it was shown that their physical properties could be improved very considerably if the domain sizes could be reduced drastically. However, in melt blending, there was a limit to the reduction of domain sizes. A noticeable improvement in properties was achieved through the use of various fillers and crosslinking agents. Small changes in crystallite size and percentage crystallinity were observed where certain additives were used. It appeared that the additives that were most effective in enhancing physical properties acted by improving load transfer at the interface between the two polymer phases.

The effect of domain size on the hardness of ordered VC 0.84

It is now well known that VC 0,84 and some other substoichiometric compositions of this carbide exhibit ordering. As might be expected the order range depends to a very great extent upon the specimen's thermal history. A systematic study has been made to determine the effect of cooling rate through the order-disorder transition range on the domain structure and subsequent room temperature hardness. The hardness is found to be related inversely to the domain size. This result is analysed in terms of existing theories for grain boundary and domain boundary hardening. Substructure within the domains also increases the hardness to a lesser extent.

Imperfections in Copper‐Silicon Filings

AbstractDetailed X‐ray line‐broadening studies are made on deformed filings of Cu96Si4, Cu92Si8, Cu90Si10, and Cu89Si11 alloys. The f.c.c. deformation fault parameters in fresh filings of the first three alloys, in each case of two different grain sizes, are determined by the Paterson method. Stacking‐fault contributions to the observed diffraction broadening are eliminated by a procedure suggested by Christian and Spreadborough, and the domain size and lattice strain effects are separated by single line Fourier analysis. The fresh filings of the two‐phase Cu89Si11 alloy show only the faulted h.c.p. structure, the f.c.c. phase having disappeared during deformation by filing. The fault parameter, domain size, and lattice strain values in the strain‐induced h.c.p. phase are also estimated.