Institute Of Metal Physics Research Articles

Depth-resolved local atomic structure of Fe/Cr multilayer film with GMR effect: Experimental results

A subnanometric resolution method for studying the local atomic structure of interface and surface of low contrast multilayered nanoheterostructure thin films is applied to the Fe/Cr multilayer sample with GMR (Giant Magnetoresistance) effect. We consider combination of the X-ray reflectivity (XRR) and the Extended X-ray absorption Fine Structure (EXAFS) spectroscopy with angular resolution. The XRR experiment has been carried out according to standard procedure using a specialized X-ray diffractometer «Empyrean» at the Institute of Metal Physics (Ekaterinburg). We have applied a measurement method proposed earlier by V. P. Romanov et al. This approach allowed us to separate the diffuse and pure specular contributions. To determine the concentration depth-profile of element from XRR data, we have implemented the Levenberg-Marquardt (L-M) algorithm for nonlinear inverse problem. Thus, the phase problem for X-ray specular reflectivity has been solving. The EXAFS measurements has been performed using synchrotron facilities (National Research Centre “Kurchatov Institute”). {The Fe and Cr K absorption spectra} were recorded in fluorescence mode with angular resolution. The experimental results for depth-resolved local atomic structure of Fe/Cr multilayer with GMR effect has been obtained. A depth resolution of 2-3 Å was reached. Atomic structure of Fe and Cr atoms located at seven depth points including interface for the Al2O3/Cr(100 Å)/[Fe(8 Å)/Cr(10,5 Å)]2/Cr(20 Å) multilayered sample was obtained. It was shown what chromium oxides were present on the surface of the sample..

Коэрцитиметрический контроль качества стальных деталей. Уральская школа коэрцитиметрии

The article shows the main areas of application coercimetric NDT method. The article presents historical information about the method founders who represents the Ural scientific school of magnetism. The main limitations of the method and practical applications of one-parameter and multiparameter coercimetric techniques are shown. Problems of magnetic quality inspection of quenched and tempered steels with different carbon contents and different degrees of alloying are considered. The possibility of monitoring the quality of steel products surface hardening with the use of external converters is demonstrated. Guidelines for external electromagnet size selection in dependence on a hardened layer thickness are presented. The brief analysis of the impact of current and residual stresses on the coercive force of steel products has been fulfilled. Problems of coercimetric inspection of stresses and steel plastic deformation degree are indicated; these problems are connected with varied behaviour of the coercive force under elastic extension and at high degrees of plastic deformation in the stage of pre-destruction. The originally developed technique for coercimetric quality control of forming rolls is presented. Information about modern coercimeters developed at the Institute of Metal Physics is provided.

Transmission and scanning analytical electron microscopy: Equipment and methods of nanodiagnostics and nanometrology

In this review we focus attention on the main methodological approaches for determining and visualizing nanostructural states that can be found in compacted bulk, film, or powder materials. A classification of nanostructural and nanophase materials is discussed. The main methods of structure examination, including direct electron-microscopy studies of nanomaterials, are described. We analyze the fundamental approaches and specific features of the structure and phase nanodiagnostics and describe the main phase, structural, and morphological parameters or properties of the studied materials together with the ways in which they are represented and an estimation of the errors of their determination. The main types of modern transmission and scanning microscopes are considered from the point of view of their technical characteristics and capabilities. The microscopes include attachments for elemental, structural, and texture analyses, as well as for in situ experiments on heating-, cooling-, radiation-, and deformation-induced structural and phase transformations. Various examples of electron microscopy studies of metallic, ceramic, composite, and magnetic materials are given. They were studied by electron diffraction, texture methods, and elemental analyses. The 25-year experience of scientific research performed at Electron Microscopy Center for Collective Use, Institute of Metal Physics, Ural Branch, Russian Academy of Sciences (IMP EMCCU UB RAS), is generalized.

Models of Mutual Solubility Increasing under the Pulse Loading

Since 1975 a so-called anomalous mass-transfer in metals and alloys under pulse loading is being investigated in the Institute of Metal Physics. This phenomenon remains to be a challenge to theoreticians. Besides, one more phenomenon (observed at the same systems) was discovered – formation of metastable alloys (solutions, and, sometimes, ordered phases), with solubility limits far exceeding the equilibrium values and depending on the deformation rate. Since formation of nonequilibrium phases is also typical for alloys under irradiation, it seemed natural for us to use some of concepts and models invented in the “materials under irradiation” community. We propose 3 types of models for description of metastable solid solution formation in diffusion couple under pulse loading: 1) flux balance for both components at the interface with account of non-equilibrium defects generated during pulse loading; 2) “ballistic jump” concept, which had been invented by George Martin et al. for materials under irradiation or ball-milling, combined with another Martin’s kinetic model (1994) of diffusion; 3) modification of such a concept for the case of non-equilibrium interstitial defects. Non-equilibrium phase diagrams obtained by all 3 models are built and compared with experimental data which reflect a qualitative correspondence to one another.

Instruments for Magnetic Phase Analysis of Articles Made of Austenitic Corrosion-Resistant Steels

A brief review in the field of investigation of properties of austenitic alloys is presented. New instruments developed for nondestructive testing of the phase composition and magnetic properties of austenitic corrosion-resistant steels at the Institute of Metal Physics, Ural Division, Russian Academy of Sciences, are described. The first section of the paper is devoted to such directions as “ferritometry.” Instruments intended for the testing of magnetic characteristics of slightly magnetic steels, such as the magnetic permeability and susceptibility, are described in the second section of the paper.

ELECTRON PARAMAGNETIC RESONANCE AND FLUORESCENCE IN SITU HYBRIDIZATION-BASED INVESTIGATIONS OF INDIVIDUAL DOSES FOR PERSONS LIVING AT METLINO IN THE UPPER REACHES OF THE TECHA RIVER

Waterborne releases to the Techa River from the Mayak Production Association in Russia during 1949-1956 resulted in significant doses to persons living downstream; the most contaminated village was Metlino, about 7 km from the site of release. Internal and external doses have been estimated for these residents using the Techa River Dosimetry System-2000 (TRDS-2000); the primary purpose is to support epidemiological studies of the members of the Extended Techa River Cohort. Efforts to validate the calculations of external and internal dose are considered essential. One validation study of the TRDS-2000 system has been performed by the comparison of calculated doses to quartz from bricks in old buildings at Metlino with those measured by luminescence dosimetry. Two additional methods of validation considered here are electron paramagnetic resonance (EPR) measurements of teeth and fluorescence in situ hybridization (FISH) measurements of chromosome translocations in circulating lymphocytes. For electron paramagnetic resonance, 36 measurements on 26 teeth from 16 donors from Metlino were made at the GSF-National Research Center for Environment and Health (16 measurements) and the Institute of Metal Physics (20 measurements); the correlation among measurements made at the two laboratories has been found to be 0.99. Background measurements were also made on 218 teeth (63 molars, 128 premolars, and 27 incisors). Fluorescence in situ hybridization measurements were made for 31 residents of Metlino. These measurements were handicapped by the analysis of a limited number of cells; for several individuals no stable translocations were observed. Fluorescence in situ hybridization measurements were also made for 39 individuals believed to be unexposed. The EPR- and FISH-based estimates agreed well for permanent residents of Metlino: 0.67 +/- 0.21 Gy and 0.48 +/- 0.18 Gy (mean +/- standard error of the mean), respectively. Results of the two experimental methods also agreed well with the estimates derived from the use of the TRDS-2000. For all persons investigated according to each technique, the EPR-measured dose to enamel was 0.55 +/- 0.17 Gy, and the TRDS-2000 prediction for the dose to enamel for these individuals is 0.55 +/- 0.07 Gy. The fluorescence in situ hybridization-based dose, 0.38 +/- 0.10 Gy, compared well to the TRDS-2000 prediction of external dose, 0.31 +/- 0.03 Gy, to red bone marrow for these persons. Validation of external doses at the remaining villages is an active area of investigation.

Current state of safety testing of main pipelines

The paper briefly describes the history of quality testing of buried main pipelines. The pioneering research into the development of magnetic techniques for detection of flaws caused by corrosion in pipelines has been conducted at the Institute of Metal Physics of the Ural Division of Russian Academy of Sciences. The fairly high accuracy of measured parameters of detected flaws is confirmed. The topical problems concerning pipeline testing are formulated.

Non-Chemical Potentials and Dissipative Forces in Thermoelastic Martensitic Transformation

*Institute of Metal Physics, National Academy of Sciences of the Ukraine,Department of Phase Transitions, 36 Vernadsky Str., 252142, Kiev, Ukraine**Departament de Fi´sica, Universitat Illes Balears. E-07071 Palma de Mallorca, Spain(Received October 16, 1997)(Accepted in revised form March 6, 1998)IntroductionDuring a martensitic transformation cycle, a shape memory alloy (SMA) runs a sequence of heterophasestates in which the fraction of martensitic phase increases continuously on cooling and decreases onheating showing a definite temperature hysteresis. At each step of both the forward and the reversetransformations the microstructure of SMA consists of a great number of plate-like martensite crystalsin an austenite matrix, appearing and growing on cooling and shrinking and disappearing on heating.Started with the works by Kurdjumov and Kurdjumov & Khandros (1–3), the problem of thermoelasticequilibrium in SMA remains still opened and has been the subject of extended discussions anddevelopments (4–13). Paskal & Monasevich (8, 9) postulated the existence of fraction dependent Gibbsfree energy potentials describing the direct and reverse martensitic transformation. They also derivedconstitutive thermodynamic force balance equations accounting for the temperature dependence of themartensite volume fraction in a global hysteresis cycle through minimisation of these, strictly speaking,non-equilibrium potentials. Some problems arise from this procedure: first, considering the configura-tion dependent thermodynamic functions as solely dependent on the martensite fraction is onlyphysically reasonable provided the microstructure sequence followed during the forward martensitictransformation is followed in the opposite sense during the reverse transformation. Such “microscopicreversibility” principle was qualitatively formulated by Olson & Cohen (5), who pointed out that growthand shrinkage of the martensitic plates take place in a well defined sequential order, the first platesformed on cooling being the last ones to disappear on heating. Second, introduction of non-equilibriumfree energies containing dissipative or frictional terms, and especially application of minimisationprinciple to them can be a source of misleading physical conclusions. Finally, the usual splitting of thefraction dependent thermodynamic potentials into pure chemical and non-chemical (elastic) compo-nents is practically useful, in the sense of their determination from the experiment, only if the purechemical equilibrium temperature T

Structure and hardness of steel 05 subjected to cold forging and heat treatment

Connective structural elements of pipelines (reducers, flanges, etc.) widely used in the chemical and fuel power industries are commonly manufactured by hot forging. However, this method has a low technical and economic efficiency. The Institute of Metal Physics of the Ural Branch of the Russian Academy of Sciences has developed a process of cold forging for manufacturing preforms of pipeline flanges.

5th International Conference on Electron Spectroscopy Institute of Metal Physics, Kiev, Ukrain, July 26–August 1, 1993

5th International Conference on Electron Spectroscopy Institute of Metal Physics, Kiev, Ukrain, July 26–August 1, 1993