Analysis Of Line Breadths Research Articles

Structural and Morphological Study of a Series of Ball Milled Nanocrystalline Fe<sub>1-<i>x</i></sub>Al<sub><i>x</i></sub> (0.3 ≤ <i>x</i> ≤ 0.6) Alloys

In the present manuscript, the authors have systematically investigated the structural and morphological properties of a series of mechanically alloyed Fe1-xAlx (0.3 ≤ x ≤ 0.6) samples using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). All the samples, after 5 hr of milling, show crystalline structure, irrespective of the constituent concentration and are textured mainly along (110) direction. In Fe-rich samples, the formation of an off-stoichiometric Fe3Al phase is favored and in case of Al-rich samples, both Al-rich phases and clustering of Al atoms are present. Analysis of line breadths was carried out to get an insight into the interrelated effects of average crystallite size, and lattice parameters. The grain size of constituents was decreased to the nanometer range (between 6 - 8 nm) and the constituents dissolved at the nanograin boundaries. Similar conclusions were also revealed from the SEM results which show that the initial shape of particles disappeared completely, and their structure became a mixture of small and large angularshaped crystallites with different sizes. The results of this research could be directly employed in the design of deformation schedules for the industrial processing of Fe-Al alloys.

X-ray studies of structure defects in nanostructured FeAl alloy

The evolution of the microstructure of the mixture iron and aluminium powders during the high energy mechanical alloying process was investigated by X-ray line profile analysis. Analysis of line breadths was carried out to get an insight into the interrelated effects of grain size, lattice strain and dislocations. The final product of the MA process was the nanocrystalline Fe(Al) solid solution with a mean crystallite of 10 nm. On the basic on the modified Williamson–Hall plots, the root-mean squared strains were explained by the presence of dislocations, with a dislocation density of about 6 × 10 16 m − 2 . The identified steady-state saturation values of these parameters can be related to accumulate strain hardening of the powder material during longer milling times.

Dislocations and grain size in ball-milled iron powder

The microstructure of ball-milled iron powder has been investigated by high resolution X-ray line profile analysis. Analysis of line breadths suggested that the contrast factors related to dislocations have to be taken into account in the Williamson-Hall procedure. This concluded to a modified Williamson-Hall plot which provided, in a straightforward manner, the grain size refinement of nanocrystals ball-milled for different periods of time. At the same time it has been shown that strain broadening, even in these nanoscale small-grain particles, is caused by the presence of dislocations. The line profiles were also studied by the method of Fourier analysis, which gave the absolute values of dislocation densities.

High resolution diffraction studies of microstructure in YBa 2Cu 3O 7- δ

High resolution powder diffraction has revealed that the separation of twins can be approximately modelled from hkl reflections through the analysis of line breadths. A bulk average twin separation was found to be of the order of 500 Å. Analysis of hhl line breadths indicates that a fault occurs every 1300 Å in the (110) direction. Single crystal X-ray diffraction (XRD) analysis shows that these faults are likely to occur along the direction where the (110) planes are coherent with the twin plane. Single crystal XRD analysis also demonstrated the relationship between twin colonies of opposite orientation. Further analysis revealed that low angle boundaries are likely to exist within a crystal. These low angle boundaries are probably between domains that are some hundreds of microns in size.

The application of the convolution relations in the X-ray line breadth analysis. III

For pt.II see ibid., vol.9, no.4, p.593 (1976). Direct evaluations of the particle size L and strain parameters e are made following an iterative method. The expression derived previously for the observed integral breadth on the basis of simultaneous convolutions of the Gaussian instrumental profile with Schoening's true diffraction profile (which originates from a Cauchy particle size profile and a Gaussian strain profile) is considered for this purpose. The agreements of both L and e values evaluated directly with the predetermined ones have been found to be fairly good and this conforms with the observations made previously.

The application of the convolution relations in X-ray line breadth analysis. II

For pt.I see ibid., vol.8, no.7, p.731 (1975). The theoretical expressions for the integral breadth of experimentally observed profiles are derived following a simultaneous convolution of Schoening's true diffraction profile which originates from the Cauchy particle size profiles and the double-square or Gaussian strain profile. The instrumental profile has Gaussian, Cauchy, intermediate exponential and double-square functional forms, and is applied to profiles of cold-worked FCC alloys and vapour-deposited silver films. It is observed that in the case of films a fairly good agreement to within 2% exists for the Gaussian form of the instrument profile convoluted with the alternative approach for Schoening's true profile. In the case of alloys where both the particle size and strain effects are high, this particular convolution cannot be applied at all due to the nature of the derived expression.

The application of the convolution relations in the X-ray line breadth analysis. I

An X-ray diffraction profile resulting from microstructural changes in materials is a convolution of the instrumental and the true diffraction profile. The simultaneous convolutions of the functional forms representing the respective profiles are dealt with. The convolution of schoening's true diffraction profile, originating from the cauchy particle-size profile and the guassian strain profile with the instrumental profile having several functional forms (namely, gaussian, cauchy and an intermediate exponential one), has been examined and applied to profiles of several cold-worked alloys and vapour-deposited silver films. A fairly good agreement for the calculated and experimental integral breadths of the profiles has been observed for a gaussian instrumental function. The analysis gives a confirmation of the functional forms assumed and also of the schoening's particle size and strain parameters.

Stacking fault probabilities in b.c.c. Zr-Mo alloys

Abstract Beta Zr-Mo alloys containing 2, 4 and 6% Mo were quenched from 960°C and deformed by filing. X-ray line-breadth analysis revealed that the presence of stacking faults is a factor contributing to particle-size broadening. The compound fault probability (1·5α+β)/1·5 increased with Mo content, indicating a probable decrease in the stacking fault energy of b.c.c. zirconium alloys with increase in Mo content.

Anti-phase domain growth kinetics in β′ phase AgZn

Anti-phase domain growth was studied in a quenched β′ phase Ag-43 atom % Zn single crystal. X-ray line breadth analysis showed that the domain growth rate changes over a five decade range within the temperature interval 23 C to 99 C. The experimentally determined growth kinetics are substantially different from those found in other alloy systems and from those predicted by theory.

A Study of Defects Due to Surface Processing in Silicon by Means of X-Ray Extinction Contrast Topography

AbstractIn order to study the effects of processing variables on the defect contents of silicon wafers, an X-ray extinction contrast camera was designed and constructed to fit on the standard GE XRD-5 table. The camera, in its normal operating position, can be routinely used without interfering with the emission or diffraction instrumentation of the unit, and also can be mounted on the diffractometer stage for diffraction line breadth analysis. Routine laboratory procedures including sample preparation and mounting, film types, and film exposure and development are outlined.The correlation between extinction contrast topographs and optical photographs of sawed wafers is presented. Wafers were examined in the sawed, lapped, and chemically polished conditions. Subsequent to each processing step in the surface treatment of wafers, a series of topographs was made using four different crystal orientations. In this manner the three-dimensional picture of the defects is obtained, as are the Burger's vectors of all dislocations. It appears that internal defects such as dislocations are more uniformly distributed in lapped and chemically polished wafers than in sawed and chemically polished wafers. Furthermore, different doping impurities and levels cause different amounts of contrast in the dislocation images.

X-ray line-breadth analysis of growth and deformation faulting in hexagonal close-packed structures

Approximations employed so far in the evaluation of growth and deformation faulting in h.c.p. structures from integral and half-peak X-ray line breadths have been critically examined. An improved and yet simple procedure has been suggested to study faulting, mixed or otherwise, in h.c.p. structures. Necessary corrections for limitations of the measuring range have been worked out for integral and half-peak breadths over a wide range of growth and deformation fault parameters. The suggested procedure is illustrated by application to a study of faulting in spontaneously transformed cobalt powder.

X-ray Line-Breadth Analysis of Deformed Metallic Structures

X-ray Line-Breadth Analysis of Deformed Metallic Structures

Simplifications in X-Ray Diffraction Line Breadth Analysis

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