X-ray Line Breadth Research Articles

Fatigue damage monitoring of laser surface treated steel by X-ray diffraction methods

The evolution of fatigue damage in an austenitic stainless steel was investigated by metallographic and X-ray diffraction (XRD) methods. The experimental results confirm a previously developed idea based on X-ray line breadth measurements. According to this idea, the operating mechanism for fatigue damage is the progressive work hardening of the material which takes place preferentially at the surface and advances gradually into the bulk. Fatigue fracture is related to the attainment of a critical work hardening level at the surface. The so called integral breadth of the XRD line was taken as an estimate of work hardening. In the present work the X-ray line integral breadth was used to monitor the accumulated work hardening of laser surface treated and untreated specimens during fatigueand is proposed as a non-destructive fatigue damage parameter. It is also shown that the map of the surface damage resulting from integral breadth measurementson broken specimens gives iriformation about the microstructure and fatigue damage evolution. Particularly, the change in the damage accumulation after laser surface treatment is related to the microstructural changes caused by the treatment.

Effects of isovalent substitutions on lattice softening and transition character of BaTiO3 solid solutions

The transition character of paraelectric-to-ferroelectric phase transition and its relation to lattice soft-mode behavior in the solid solutions of (Ba,Sr)TiO3, (Ba,Ca)TiO3, Ba(Ti,Zr)O3, and Ba(Ti,Sn)O3 were investigated by the measurements of dielectric constants in the temperature range from −30 to 150 °C, and x-ray line breadth of 100, 110, and 111 Bragg reflections at temperatures above the transition point. From the result of dielectric measurement, it was found that the specimens containing Ti-site substituents have shown a diffuse phase transition character, whereas those having Ba-site substituents have preserved a sharp phase transition. It was also noted from the change of line breath of Bragg reflections that for the solutions of Ba(Ti,Zr)O3 and Ba(Ti,Sn)O3, the high dynamic strain at the 〈1 0 0〉 axis, induced from the soft-mode of lattice vibration, become repressed when a large amount of solutes is contained, but for the solutions of (Ba,Sr)TiO3 and (Ba,Ca)TiO3, it is recovered at temperatures near the transition point. Moreover, the dynamic strain at the 〈1 1 1〉 axis can be rapidly repressed by the addition of Ti-site substituents. The different effects on the dynamic strains are attributed to the disparate distortions of oxygen octahedra in the perovskite lattice, induced by the solutes of different site substitution. It is also believed that the influence on the soft-mode of lattice vibration has caused the different phase transition characters of the four BaTiO3 solid solutions.

Anomalous X‐ray Line Broadening Observed in γ‐Fe2O3 Derived from γ‐FeOOH

Defect structure of fine‐grained γ‐Fe2O3 powder obtained by dehydroxylation of y‐FeOOH powder has been studied by X‐ray diffraction and high‐resolution electron micrographs. An anomalous X‐ray line broadening was observed in the γ‐Fe2O3 powder. It is found that the X‐ray line breadth is dependent on the crystal structure factors of each reflection line: the reflections from net planes consisting of only metal ions on tetrahedral sites and octahedral sites of spinel structure are much broader than those from net planes including oxygen ions. The anomalous X‐ray line broadening is explained on the basis of stacking faults in the spinel structure.

X-Ray Diffraction Study of Phase Formation and Growth in Nitrogen Implanted Iron: Temperature Effects

ABSTRACTWe report preliminary results from an ongoing study of iron nitride grains formed in high purity iron under nitrogen ion bombardment. Under various implantation conditions, different iron nitride phases grow large enough to produce sharp x-ray diffraction lines. We have used these lines to examine the influence of target temperature during implantation. Between 200°C and 400°C increasing target temperature, which enhances dopant mobility, reduces the retained dose of nitrogen and restricts the formation of nitride phases. Over this temperature range, however, increasing vacancy mobility favors the growth of nitride grains and x-ray line breadth data suggests an optimum temperature for growth of Fe4N grains.

Subcritical thermomechanical treatments of eutectoid steel

The kinetics of annealing of eutectoid steel which was 75% cold rolled and then annealed at temperatures of 400, 500, and 600°C have been examined using measurements of microhardness, X-ray textures and line broadening, scanning and transmission electron microscopy, and positron annihilation. The controlling process appears to be the diffusion of Fe along Fe3C/α Fe interfaces. The polygonization of ferrite, the formation of recrystallized ferrite grains, and the spheroidization of Fe3C were observed. Major changes in positron and X-ray line breadth parameters within the first 10–100 s indicate very rapid initial recovery but it is not clear if subsequent changes in those two parameters are a result of recrystallization only or of overlapping recovery and recrystallization processes. Although some degree of spheroidization was involved in each of the anneals, the positron and X-ray line broadening were selective in that they detect changes in the ferrite only.

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.

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.

Characteristic features of the hot and cold pressing of powder preforms

1. It is shown that high-density molybdenum with a fine-grained structure can be produced by cold and hot pressing under ultrahigh pressure. The optimum UHP pressing pressure has been established. 2. As a result of microhardness and x-ray line breadth measurements, it is demonstrated that pressing induces strain hardening in compacted Mo powder, the resultant dense material being one and a half times to twice as strong as cast Mo. The strain hardening is preserved right up to the initial recrystallization temperatures (∼1000–1200°C). 3. Vacuum heat treatment at T≥1400°C after UHP pressing enables a comparatively ductile sintered Mo material to be obtained, which can subsequently be subjected to room-temperature plastic working. The heat treatment time is appreciably less than the time required for sintering such a material in the usual manufacturing process.

Untersuchung über die Begrenzung röntgenographisch ermittelter Teilchengrössen

Changes of particle size and strain during annealing of cold-worked aluminum powders have been determined by measuring X-ray line breadths. Aluminum powders ground under special conditions show a decrease in particle size as well as a reduction of strains within certain ranges of temperature. This is due to polygonization processes and allows conclusions to be drawn regarding the limits of coherent regions of X-ray diffraction. The X-ray measurements were supplemented by electron microscope studies.

X-Ray Analysis of Fatigue Softening in Cold Worked Copper

AbstractThe recovery and recrystallization of cold rolled copper during reverse bending fatigue at room temperature has been studied with x-ray diffraction, optical microscopy and transmission electron microscopy techniques. Recovery of x-ray line breadth was recorded as a function of number of cycles at all strain amplitudes investigated. Recrystallization was observed to take place only at small strain amplitudes (life of 106 to 107 cycles). The rate of nucleation of the recrystallized grains increases with increasing strain amplitude and is a linear function of the number of cycles. The formation and growth of the grains was confined to regions near the surface of the specimen. Since comparable thermal recovery occurs at approximately 435°F it is concluded that the dynamic generation and migration of numerous point defects during fatigue is responsible for the room temperature recrystallization.

A transient effect in grain-boundary migration during recrystallization in aluminum

The growth of grains during early stages of recrystallization at 65°, 100° and 187°C in 99.99 + % pure aluminum rods extruded at sub-zero temperatures has been studied. Two stages of growth were noted for grains whose crystallographic orientations may be described as a scattered 〈114̄〉 - 〈012〉 with respect to the fiber axis of the rod. A transient-growth stage occurred at early times and was characterized by very high boundary migration rates initially which decreased by 10 5 during isothermal annealing. The ensuing growth was characterized by a slow, steady-state boundary velocity. The duration of transient growth depended on the annealing temperature being longer at the lower temperatures. The grain diameter reached during transient growth was larger the higher was the temperature of annealing. Pre-annealing at 24°C reduced the grain diameter achieved on subsequent annealing at 100°C. The X-ray line breadth of cold work recovered 20% during the transient-growth period at 100°C. Two possible interpretations of the observed transient effects are discussed. These involve the role of residual impurities and the excess vacancies generated by plastic deformation.

Evaluations of particle size and strain values from X-ray line breadths and line shapes in α-AgCd alloys

Evaluations of particle size and strain values from X-ray line breadths and line shapes in α-AgCd alloys

Uncertainties in crystal size computed from the standard deviation of the X-ray line breadth

Uncertainties in crystal size computed from the standard deviation of the X-ray line breadth

Strain and particle size values from X-ray line breadths

Strain and particle size values from X-ray line breadths

X-Ray Yield and Line/Background Ratios for Electron Excitation

X-ray yield in photons/sr/electron was measured for the Kα lines of Ti, Cr, Mn, Fe, Cu, Zn, Ge, Zr, and the Lα lines of Ta and Au. Incident electron energy was varied from 11 to 38 keV, and for some elements the take-off angle for emerging x rays was varied from 6 to 45 deg. Theoretical yield values calculated after the method of Metchnik and Tomlin showed an average deviation of about 30% from the measured values, a very satisfactory agreement. Line/background ratios were also measured for the same elements and conditions. Normalization to the natural x-ray line breadths gave ratios between 100/1 and 26 000/1 depending on the element and experimental conditions. Line/background ratios are consistently larger at low take-off angles indicating that the characteristic radiation must be generated relatively closer to the surface than the continuum of the same wavelength.

サッカリンのニッケル電着応力におよぼす影響について

The effect of saccharin on the stress of Ni electroforming from high concentration Watt's dath, is studied by spiral contructometer and X-ray diffraction method.As the concentration of saccharin is increased (0 to 100mg/l), the stress measured with spiral contructometer, is changed from tensile to compressive stress, whereas the half-peak breadth of X-ray diffraction line is increased, but with a further increase of saccharin concentration (100 to 1, 000mg/l), the stress and half-peak breadth are almost unchanged, The crystal size measured by electromicroscopy and X-ray diffraction techniques are about 1 to 5 microns, and the increase of X-ray line breadth seems to be due to strain of crystals.

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