Quantitative Phase Analysis Method Research Articles

Quantitative X-ray Rietveld analysis of metallic aluminum content in nano-aluminum powders

Accurate analysis of the content of metal aluminum (Al) in nano-Al powders is a difficult task due to the high reactivity of nano-Al powders. Here, the X-ray Rietveld quantitative phase analysis (QPA) method was applied to analyze the content of metal aluminum in nano-Al powders produced by three methods. A good agreement between the observed and calculated diffraction pattern was obtained and the conventional Rietveld factors (R p, R wp and GOF) converged to satisfactory values, which suggested that Al content was evaluated accurately. At the same time, the mixture sample of 89.77 wt.% micro-Al + 10.23 wt.% α-Al 2O 3 was study and the fitting pattern and R factors were satisfactory, which further verified the reliability of the X-ray Rietveld QPA method.

Variation of the X-ray quantitative phase analysis method

A method to determine the composition of the phase coequilibrium with one of the components in the system under study is proposed. It is based on the use of diffraction pattern data for test samples whose representative points are located at different sides of the point of the phase in question.

Comprehensive phase characterization of crystalline and amorphous phases of a Class F fly ash

A comprehensive approach to qualitative and quantitative characterization of crystalline and amorphous constituent phases of a largely heterogeneous Class F fly ash is presented. Traditionally, fly ash composition is expressed as bulk elemental oxide content, generally determined by X-ray fluorescence spectroscopy. However, such analysis does not discern between relatively inert crystalline phases and highly reactive amorphous phases of similar elemental composition. X-ray diffraction was used to identify the crystalline phases present in the fly ash, and the Rietveld quantitative phase analysis method was applied to determine the relative proportion of each of these phases. A synergistic method of X-ray powder diffraction, scanning electron microscopy, energy dispersive spectroscopy, and multispectral image analysis was developed to identify and quantify the amorphous phases present in the fly ash.

Adaptation of the X-Ray Diffraction Technique to the Analysis of Residual Stress in Carbo-Nitrided Steel Layers

X-ray diffraction is used to analyse the fatigue behaviour of carbo-nitrided steel layers. Measurements are therefore carried out on the two major phases of the material, i.e. the martensite (a') and the retained austenite (g). On such gear material, X-ray residual stress evaluations are particularly difficult for three reasons. First, the studied material is multiphase. For that reason, in each phase, the stress component in the direction normal to the surface is non negligible. Second, the diffraction peaks obtained on the martensite are broadened, due to the overlap of different reflections of the tetragonal structure. Third, the material contains also carbide and nitride clusters, which lead to incoherent and diffuse scattering of X-rays thus making quantitative phase determination difficult. In our paper the methods used to solve these problems are presented. The development of a new quantitative phase analysis method which accounts for the variation of diffuse scattering of X-rays is shown first. The second part deals with an iterative micromechanical model implemented for the evaluation of the carbon content and the residual stress components of each phase. These methods are used for analysing the evolution with cycling fatigue of all the parameters derived from our enhanced analysis (phase volume fraction, carbon content, stress components, peak width).

Phase evolution and kinetics of the oxidation of monosulfide solid solution under isothermal conditions

In this work, the effects of stoichiometry on phase evolution during the oxidation of mss (monosulfide solid solution) were investigated. A series of mss samples, ranging from Fe 7.9S 8 to Fe 2.37Ni 5.53S 8 were synthesized from pure components. Samples with grain size 53–90 μm were oxidized at 830 and 850 K in air in a muffle furnace. The Rietveld quantitative phase analysis method was used to identify and quantify the phase information from powder X-ray diffraction (XRD) profiles. Hematite was observed and accounted for most of the oxidized iron. Nickel in mss was not oxidized to NiO under current isothermal conditions; instead, it was finally transformed to Ni 17S 18. Hematite, Fe 2(SO 4) 3 and residual mss were identified in the final phases after 24 h oxidation of the mss composition Fe 7.9S 8; hematite and Ni 17S 18 for compositions Fe 6.15Ni 1.54S 8 and Fe 2.37Ni 5.53S 8; hematite, Ni 17S 18 and pentlandite for Fe 6.4Ni 1.6S 8. Given a constant iron to nickel atomic ratio of 4:1, the sample with lower metal concentration, Fe 6.15Ni 1.54S 8, showed a faster oxidation rate than its metal richer counterpart, Fe 6.4Ni 1.6S 8. The mean oxidation rates for these two samples are 1.85 × 10 −4 and 1.22 × 10 −4 s −1 respectively for 1.5 h heating at 830 K. Vyazovkin's theory of changing activation energy ( E a) with reaction extent ( y) was employed in the current kinetic study. The activation energy was determined using a model-free method. The oxidation of Fe 6.4Ni 1.6S 8 exhibited a higher E a than Fe 6.15Ni 1.54S 8 over the course of reaction. The activation energy increases with y from 67.1 to 103.3 kJ mol −1 for mss composition Fe 6.15Ni 1.54S 8; 76.1 to 195.0 kJ mol −1 for Fe 6.4Ni 1.6S 8. Bulk compositions Fe 7.9S 8, Fe 2.37Ni 5.53S 8 were selected to give a constant metal to sulfur atomic ratio of 7.9:8. Oxidation of Fe 2.37Ni 5.53S 8 achieved equilibrium within 1 h, compared to 5 h for Fe 7.9S 8.

On the accuracy of the X-ray diffraction quantitative phases analysis method in Inconel 718

Inconel 718, a widely used Nb-modified nickel-base superalloy, consists of quite a few phases in the matrix such as δ, γ ′, γ ′′ and NbC, as well as small amounts of α-Cr, TiC, NbC, TiC, etc. Because of the determinant effects of the content of δ, γ ′ and γ ′′ phases in the microstructure on the mechanical properties of this alloy, many efforts have been focused in the aspect of quantitative phase analysis [1–4]. In our previous study [5], a simple X-ray diffraction quantitative phase analysis method for Inconel 718 has been proposed based on the relationship between the lattice constant of the γ phase and the content of precipitates, but the accuracy of this method has not been studied in detail. In this work, quantitative analysis was performed using X-ray diffraction method and selective electrolysis method, and the results were compared directly. The composition of as-received Inconel 718 is shown in Table I. Specimens under five different conditions were used. Condition A: solution at 970 ◦C for 1 h, a.c., then cold rolled to 40% reduction in thickness followed by a standard double aging (720 ◦C, 8 h + 620 ◦C, 8 h). Condition B: solution at 970 ◦C for 1 h, a.c., then cold rolled to 40% reduction in thickness, solution at 970 ◦C for 1 h, a.c., again cold rolled to 40% reduction followed by the double aging. Condition C: solution at 970 ◦C for 1 h, ac, cold rolled to 25% reduction in thickness, then solution at 970 ◦C for 1 h, a.c., again cold rolled to 25% reduction followed by the double aging. Condition D, E: sampled from different positions of a turbine disc after forging, then solution at 970 ◦C for 1 h followed by the double aging. The samples for XRD quantitative analysis were mechanically polished followed with chemical etching. Quantitative analysis was performed in D/max-rB X-ray diffractometer with Cu Kα radiation. In detail see [5]. For the chemical quantitative analysis, extracting procedures of δ, γ ′ and γ ′′ phases from the matrix via selective electrolysis are as following. Extracting precipitates of γ ′, γ ′′, δ and NbC from the matrix via

Electrical properties of composites as affected by the degree of mixedness of the conductive filler in the polymer matrix

AbstractThe development of the electrical properties of composites as a function of the degree of mixedness of a conductive filler distributed into an insulating polymer is investigated. A wide‐angle X‐ray diffraction (WAXD)‐based quantitative phase analysis method was used to characterize the variations of the concentrations of the insulating binder and the conductive particles around their mean values as a function of mixing time in an intensive batch mixer. Increasing the time and hence, the specific energy input, during the mixing process results in a more homogeneous spatial distribution of the conductive filler in the polymeric matrix, which in turn results in a decrease of the volume conductivity of the composite. The decreasing conductivity of the composite is attributed to the better coating and hence the isolation of the conductive particles from each other, thus hindering the formation of a conductive network “percolation”. Overall, these results suggest that the control of the electrical properties of conductive composites could benefit from a good understanding and adequate control of the dynamics of the mixing process and the resulting degree of mixedness of the conductive particles in the polymer matrix.

Contribution to X-ray analysis of carbo-nitrided steel layers

The non-destructive X-ray diffraction method is used to analyse carbo-nitrided steel layers after wear testing. These measurements are carried out on the two major phases of the material,i.e.the martensite and the retained austenite. Such measurements are particularly difficult for three reasons. First, strong gradients exist across the wear track. Second, the diffraction peaks obtained for the martensite are broadened, as a result of the overlap of different reflections of the tetragonal structure. Third, the studied material is multiphase. Its major phases are martensite and austenite, but it also contains carbide and nitride clusters, which lead to incoherent scattering of X-rays. A new quantitative phase analysis method is thus proposed to define the volume fractions of these different constituents of the material. This method accounts for the evolution of the background level during wear. A micro-mechanical model is then developed to process the diffraction peak positions obtained for the martensite and the retained austenite. This model defines the `true' stress and carbon content of both phases. It also allows separation of the reflections of the martensite. The true widths of the diffraction peaks, which characterize the plastic deformation, can thus be quantified. Results for wear-test specimens show a strong plastic deformation of the retained austenite during contact fatigue. This leads to a partial transformation of this phase into martensite. In the martensite, on the contrary, the plastic deformation remains low but the carbon content decreases. This is caused by a stress-induced precipitation of carbides.

Quantitative phase analysis of duplex stainless steel using incomplete pole figures

The use of a single, accurate, and relatively quick experimental method suitable for determination of crystallo graphic texture and amounts of phases in the final product is of interest to some manufacturers. The suitability of an X-ray method for this purpose is evaluated in the present paper. The Schulz back reflection technique has been used to record incomplete pole figures of ferrite and austenite in a sample of commercial duplex stainless steel tube. The orientation distribution function was calculated for each phase and then used for the reproduction of complete pole figures. The complete pole figures were applied in quantitative phase analysis (QPhA), by a new method, free from texture induced errors. For comparison, the volume fraction of austenite and ferrite was also determined by means of the classic direct comparison method of Averbach and Cohen as well as by standard quantitative metallography. The proposed method of QPhA was applied for the examination of the amount of retained austenite in certain bearing construction elements.

Accurate quantitative analysis of clay and other minerals in sandstones by XRD: comparison of a Rietveld and a reference intensity ratio (RIR) method and the importance of sample preparation

AbstractX-ray diffraction is used widely for quantitative analysis of geological samples but studies which document the accuracy of the methods employed are not numerous. Synthetic sandstones of known composition are used to compare a ‘routine application’ of a Rietveld and a reference intensity ratio (RIR) method of quantitative phase analysis. Both methods give similar results accurate to within ~±3 wt.% at the 95% confidence level. The high degree of accuracy obtained is believed to depend to a large extent on the spray-drying method of sample preparation used to eliminate preferred orientation.

Quantitative Phase Analysis by X-ray Diffraction of Multiphased Binary Alloy Coatings: Application to Brass Coating

A quantitative phase-analysis method is proposed to analyse by X-ray diffraction multiphased thin films obtained by diffusion. Intensity corrections taking into account the spatial distribution of the different phases, and computing of phase concentrations without standards are presented. It is shown that important errors can be made if one does not take the nonhomogeneity of phase distributions into account. As an example, the quantitative phase analysis of a brass layer obtained by a diffusion process is given.

The effect of peak choice on the quantitative phase analysis of the Egyptian kaolins using the standardless method

The “standardless” quantitative phase analysis method proposed by Rius, Plana, and Planques [J. Appl. Cryst. 20, 457 (1987)] was evaluated by applying it to two series of artificial samples. The method was then applied to determine quantitatively the phases present in six different natural kaolin samples from Egypt. Two kaolinite peaks were selected for this analysis: One of them is known to be affected by stacking disorder, the other one is the 001 basal reflection, which is not significantly affected by stacking disorder. The method was also applied to samples of different mesh sizes. The results obtained when using the basal reflection showed that Egyptian kaolin is mainly kaolinite (82%–95%) together with anatase (2%–9%), rutile (1%–6%), and quartz (0.5%–7%). These analyses agreed very well with those obtained by chemical analysis. On the other hand, the analyses of the phases obtained from the peak which is strongly affected by stacking disorder were totally different. It was found also that by decreasing the particle sizes of kaolin samples the phase abundance of kaolinite increases, whereas those of quartz and anatase decrease. The results showed also that the standardless method is only applicable to peaks that are not strongly affected by structural disorder.

A method of quantitative phase analysis using reference samples with absent phases

X-ray diffraction quantitative phase analysis is a technique widely used in materials science and engineering research. The method proposed by Zevin [L. S. Zevin, J. Appl. Cryst. 10, 147 (1977)] has proven very useful in practice because standards or pure crystalline phases are not needed, but, Zevin only described the case ofnsamples, each of which contain different concentrations of the samenphases. An extension of this method, in which the reference samples could contain less phases than the analyzed sample is proposed in this paper. The absence of phases in reference samples is not arbitrary but depends on certain conditions. The conditions required to solve the equations are discussed in detail using the concepts of the set theory, and the results of confirmation experiments agree well with the theory.

Quantitative Estimation of Crystalline Phases of Cordierite- Mullite Based Kiln Furniture by X-ray Diffraction Method

Thermal endurance of ceramics as refractory support is closely related to the crystalline phases present. In the alumino-silicate refractory family, cordierite-mullite system, produced by using commercially available raw materials, offers an attractive proposition up to a temperature range of 1280°C. Cordierite body formed in situ with high expansion grog as additives contains the following crystalline phases: (i) cordierite; (ii) mullite; (iii)α-Al2O3; (iv) cristobalite and (v) quartz. Of these, only the first three phases are relevant in enhancing the life cycle of kiln furniture vis-a-vis their thermal endurance. Hence a quantitative phase analysis is necessary to predict the life of kiln furniture and improve upon their performance. The present method of quantitative phase analysis is applicable where the crystal structure of the component phase whose proportionate analysis in a phase mixture is required, is known. Simulated intensity patterns based on the crystallographic data, viz. space group symmetry, lattice parameters, positional coordinates of various atoms and their occupancy factors, crystal density etc, were prepared for each reflection zone. Relevant computer programmes were developed at CGCRI. The intensity data collected in different 2θ zones were used for finding the volume concentrations of different phases. The error in quantitative estimation of phases was nearly 6% when the diffraction data were taken using monochromatic X-radiation. The chemical analysis corroborates this result. The materials contained a certain amount of glassy phase. Assuming that the glassy phase was composed mainly of silica glass along with other impurities, the result showed that only 85% of the total phase was crystalline and the remaining part was amorphous.

A Method for Quantitative Phase Analysis of Silicon Nitride by X-Ray Diffraction

AbstractThe relative intensities ratios for the determination of the relative amounts of alpha and beta phases in silicon nitride and the relative amounts of delta yttrium disilicate (Y2Si2O7) and nitrogen apatite [Y5(SiO4)3N] are reported. These constants were determined using an iterative method applicable when the pure phases are not easily prepared. In addition, a calibration curve was obtained for the quantitative measurement of free silicon in silicon nitride over the range 0 to 0.3% by weight of Si.

A Method for Quantitative X-Ray Phase Analysis Without Standards

AbstractAn expanded X-ray quantitative phase analysis method is presented. It is an extension of the method without standards. In order to get the method applied more extensively, there is a discussion at the end of this paper of the suitability of samples.

ChemInform Abstract: Application of an Electroanalytical Method to Metal Phase Analysis.

AbstractThe etching quantitative phase analysis method is studied (experimentally and theoretically) and a way of eliminating the phase particle size effect on the analysis signal is found.

Application of an electroanalytical method to metal phase analysis

An electroanalytical method for the determination of precipitated phases in steels and alloys, the etching quantitative phase analysis method, has been studied. An electric signal accompanying the selective anode solution process of a phase in steel serves as the analysis signal. A way of eliminating the phase particle size effect on the analysis signal has been found. Quantitative analysis equations valid under every polarized condition of avoidable particle size effect have been derived. These equations are confirmed by experimental results and find an application in the phase analysis of steels and alloys.

Optimizing the Calculation of Standardless Quantitative Analysis

A method for quantitative phase analysis without standards (QPAWS) has been published in 1977 and has gained considerable interest, as the calibration for quantitative XRD may sometimes be difficult. Standards for quantitatative XRD are not generally available, and in many cases even the pure phases cannot be obtained.The QPAWS method is based on (i) analysis of all phases present in the samples, (ii) foreknowledge of mass absorption coefficients (MAC)(iii) measuring samples which contain all phases in varying concentrations. In this method the number of samples used is equal to the number of phases to be analysed.

Quantitative Phase Analysis of Mixtures Containing α‐, β‐Tungsten and WO2

AbstractFor incandescent lamp wire fabrication various powder metallurgical steps are necessary. The stepwise reduction of WO3 to the tungsten metal powder is one of these. During reduction chemical reactions take place under participation of doping elements (K, Si and Al) causing the structure of non‐sag wires. The origin of secondary β‐W like an indicator for the activity of dopings has been attributed importance. Therefore it has been developed a method for quantitative phase analysis of α‐W, β‐W, WO2 mixtures consisting of oxidation value determination to establish the WO2 content and X‐ray phase analysis for a quantitative separation of the α‐W and β‐W content. The influence of extinction effects caused by particle size has been investigated and it is proposed a correction method of the measured integral intensities as a function of half‐width of the (110) α‐W reflex. In regard of the obtained results the formation of the tungsten suboxide W3O has been excluded.