X-ray diffraction investigations on evaporated iron films

The structure of thin iron films of thickness about 1500 Å was studied by means of X-ray diffraction analysis. Evaporation and X-ray examination were carried out in the 10^?10 Torr range without exposing the films to the atmosphere using a recently developed ultrahigh vacuum diffraction chamber. The films were deposited onto glass substrates at a rate of 10 Å min^?1 at room temperature and were subsequently annealed at 320°C. They show a (110) fibre texture with a mean crystallite size of the (110)-oriented crystals that was distincly smaller than the film thickness. The lattice parameter was found to be always less than the corresponding value for a bulk iron standard, which can be ascribed to the formation of thermally induced strains.     

In-situ high temparature X-ray diffraction studies of nanocrystalline iron carbides

Three samples of passivated ultrafine iron carbide particles, synthesized by laser induced pyrolysis of gaseous precursors were examined by in-situ high temperature XRD during and after high temperature (600°C) treatment under UHP He atmosphere. The results indicated that the particles sintered around 400°C, with the preservation of the carbide structure dependent on the precursor composition and the amount of retained oxygen from passivation and synthesis. Transformation of the carbide to α-Fe around 400°C was dependent on the precursor purity, temperature and type of gaseous exposure. Preservation of the carbide structure on heating was dependent on the purity of the carbide, and the concentration of oxygen and carbon in the particles. A topotactic transformation from Fe₇C₃ to Fe_0.98O was observed in the case of samples studied under UHP He, which was absent in the other two treatments and is discussed relative to the as-synthesized/passivated particles composition and structure. This topotaxy leads to the selective formation of γ-Fe₂O₃ from specific ultrafine particle carbides when treated with UHP He.     

Degradation assessment of welded joints by X-ray diffraction technique

Abstract

X-ray diffraction technique has been recognized as a useful tool for the assessment of material degradation extent after a long-time service. Framework 5 project “XPECTION” was dealing with this task with respect to high-temperature creep degradation of boiler tube steels. This paper summarizes partial results of an experimental programme concentrated on mechanical properties degradation of base metals of steel and Al-alloy test specimens of welded components as a result of fatigue loading.     

Study of microstructure in vanadium-palladium alloys by X-ray diffraction technique

Present study considers microstructural characterization of vanadium-based palladium (V-Pd) alloys, which are widely used in marine environment due to their high corrosion resistance. The X-ray diffraction line profile analysis (XRDLPA) have been used to assess the microstructure in body centred cubic (bcc) V-Pd alloys having four different nominal compositions in wt.%. X-ray diffraction line broadening analysis on V-Pd alloys has been performed by using different methods like the Warren-Averbach, double-Voigt and Rietveld methods. Finally microstructural defect parameters such as domain size (D), r.m.s. microstrain 〈ɛ ²〉^1/2, twin fault (β′), spacing fault (αɛ) and deformation stacking fault (α) were evaluated in these alloys by Fourier line shape analysis using Rietveld method in which the X-ray diffraction profiles of these alloys were described by the pseudo-Voigt function to fit the experimental data. From analysis it has been observed that twin fault, β′, and the spacing fault, αɛ, are totally absent in these bcc alloy systems because the twin fault, β′, has been observed to be either negative or very small (within experimental error limit) for these alloy systems and the spacing fault, αɛ, appears to be negative. This analysis also revealed that the deformation stacking fault, α, is significantly present in this alloy system and increases with Pd content.     

X-ray diffraction study of epitaxial zinc and cadmium films prepared by hot-wall technique

Hot-wall technique greatly improves the quality of zinc and cadmium films deposited on glass substrate. At substrate temperature the growth of such films is well ordered, showing highly preferred orientation along c-axis. However, if the substrate temperature is increased beyond certain limit, we get polycrystalline growth of the films. This shows that the growth of zinc and cadmium films on glass substrate strongly depends on the substrate temperature.     

X射线衍射技术在薄膜残余应力测量中的应用

残余应力测量在薄膜材料研究中具有重要的意义,综述了薄膜残余应力X射线衍射技术测量的研究现状,其中介绍了强织构薄膜残余应力X射线衍射测量技术;同时对由于G(o)bel平行光镜、毛细管元件及二维探测器等X射线功能附件的发展,以及同步辐射源X射线的应用而带来残余应力分析的新进展进行了介绍.     

Analysis of microstress in neutron irradiated polyester fibre by X-ray diffraction technique

Microstresses developed in the crystallites of polymeric material due to irradiation of high-energy particle causes peak broadening and shifting of X-ray diffraction lines to lower angle. Neutron irradiation significantly changes the material properties by displacement of lattice atoms and the generation of helium and hydrogen by nuclear transmutation. Another important aspect of neutron irradiation is that the fast neutron can produce dense ionization at deep levels in the materials. The polyethylene terephthalate (PET) fibre of raw denier value, 78.2, were irradiated by fast neutron of energy, 4.44 MeV, at different fluences ranging from 1×10⁹ n/cm² to 1 × 10¹² n/cm². In the present work, the radiation heating microstresses developed in PET micro-crystallites was investigated applying X’Pert-MPD Philips Analytical X-ray diffractometer and the effects of microstresses in tensile strength of fibre measured by Instron have also been reported. The shift of 0.45 cm⁻¹ in the Raman peak position of 1614.65 cm{−1} to a higher value confirmed the development of microstresses due to neutron irradiation using micro-Raman technique. The defects due to irradiation were observed by SEM micrographs of single fibre for virgin and all irradiated samples.     

X-ray diffraction measurements in high magnetic fields and at high temperatures

Abstract

A system was developed measuring x-ray powder diffraction in high magnetic fields up to 5 T and at temperatures from 283 to 473 K. The stability of the temperature is within 1 K over 6 h. In order to examine the ability of the system, the high-field x-ray diffraction measurements were carried out for Si and a Ni-based ferromagnetic shape-memory alloy. The results show that the x-ray powder diffraction measurements in high magnetic fields and at high temperatures are useful for materials research.     

X-ray diffraction measurements in high magnetic fields and at high temperatures

A system was developed measuring x-ray powder diffraction in high magnetic fields up to 5 T and at temperatures from 283 to 473 K. The stability of the temperature is within 1 K over 6 h. In order to examine the ability of the system, the high-field x-ray diffraction measurements were carried out for Si and a Ni-based ferromagnetic shape-memory alloy. The results show that the x-ray powder diffraction measurements in high magnetic fields and at high temperatures are useful for materials research.     

X-ray diffraction study of calcium nitrate tetrahydrate melt at 328 K

The hydration structure of calcium nitrate tetrahydrate, Ca(NO₃)₂ · 4.1 H₂O, melt at 328 K has been investigated by X-ray scattering and correlation method. Analysis of the radial distribution function and model fitting revealed that in the hydrate melt, a Ca²⁺ ion is surrounded by about six oxygen atoms, 4.1 of which come from water molecules at the average distance of 0.241 nm, 2.0 coming from the nitrate ions at the average distance of 0.254 nm. In the first coordination shell of the melt, the formation of a direct Ca²⁺-NO ₃ ^– correlation, such as contact ion pairs, was suggested. The hydration structure of the melt analysed was compared with that of Ca(NO₃)₂ · 3.5H₂O melt previously reported, and the decrease from nine of the reported melt to six in this melt was observed in the number of the nearest neighbour oxygen atoms around a Ca²⁺ ion. This implies that in the highly concentrated aqueous solution, the structure of the first coordination shell around the cation changes markedly with a small difference in the water molecule content.     

Direct X-ray observation of lattice parameter changes due to magnetostriction in nickel single crystal

Journal of Materials Science -     

X-ray diffraction analysis of critical parameters of failure at the bifurcation point

Translated from Fiziko-Khimicheskaya Mekhanika Materialov, No. 3, pp. 20–26, May–June, 1990.     

X-ray diffraction study on oxidized titanium iron alloys as semiconducting photoelectrodes for the production of hydrogen

The bulk and surface phase composition of oxidized titanium alloys containing 0.1 to 10 at% of iron was investigated by means of different X-ray diffraction techniques. On samples exposed to oxygen of 1 bar at 873 K for 30 minutes isotropically segregated TiO₂ (rutile) was observed. Oxygen diffusion into the bulk material led to the formation of TiO_x (alpha titanium oxide) and TiFe. Alloys treated at 1173 K for 1 hour under oxygen of 1 bar followed by a high vacuum annealing showed an inhomogenous structure of free iron, rutile and Magneli phases.     

X射线粉末衍射数据的校正

扼要介绍了X射线粉末衍射数据（峰位峰强和峰形）的校正方法和使用的标样。