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In this work, the Cu clustering in Fe under irradiation is investigated using experiments, cluster dynamics and atomistic kinetic Monte Carlo (AKMC) simulations. In experiments, cast iron and model FeCu alloy samples were irradiated with 2 MeV electrons for 143 h at 140 °C. The post-irradiation microstructure was characterized using atom probe tomography. Cluster dynamics and AKMC methods were used to sim- ulate the Cu clustering under the same irradiation conditions. Both simulation methods show satisfactory agreement with experiments, lending strength to the validity of the models. Finally, the Cu clustering in spent-fuel repository conditions for 10 5 years at 100 °C was simulated using both methods. The results indicate that potential hardening by Cu clustering is insignificant over 10 5 years., QC 20230307

In this work, the Cu clustering in Fe under irradiation is investigated using experiments, cluster dynamics and atomistic kinetic Monte Carlo (AKMC) simulations. In experiments, cast iron and model FeCu alloy samples were irradiated with 2 MeV electrons for 143 h at 140 °C. The post-irradiation microstructure was characterized using atom probe tomography. Cluster dynamics and AKMC methods were used to sim- ulate the Cu clustering under the same irradiation conditions. Both simulation methods show satisfactory agreement with experiments, lending strength to the validity of the models. Finally, the Cu clustering in spent-fuel repository conditions for 10 5 years at 100 °C was simulated using both methods. The results indicate that potential hardening by Cu clustering is insignificant over 10 5 years., QC 20230307

In this work, the Cu clustering in Fe under irradiation is investigated using experiments, cluster dynamics and atomistic kinetic Monte Carlo (AKMC) simulations. In experiments, cast iron and model FeCu alloy samples were irradiated with 2 MeV electrons for 143 h at 140 °C. The post-irradiation microstructure was characterized using atom probe tomography. Cluster dynamics and AKMC methods were used to sim- ulate the Cu clustering under the same irradiation conditions. Both simulation methods show satisfactory agreement with experiments, lending strength to the validity of the models. Finally, the Cu clustering in spent-fuel repository conditions for 10 5 years at 100 °C was simulated using both methods. The results indicate that potential hardening by Cu clustering is insignificant over 10 5 years., QC 20230307

In this work, the Cu clustering in Fe under irradiation is investigated using experiments, cluster dynamics and atomistic kinetic Monte Carlo (AKMC) simulations. In experiments, cast iron and model FeCu alloy samples were irradiated with 2 MeV electrons for 143 h at 140 °C. The post-irradiation microstructure was characterized using atom probe tomography. Cluster dynamics and AKMC methods were used to sim- ulate the Cu clustering under the same irradiation conditions. Both simulation methods show satisfactory agreement with experiments, lending strength to the validity of the models. Finally, the Cu clustering in spent-fuel repository conditions for 10 5 years at 100 °C was simulated using both methods. The results indicate that potential hardening by Cu clustering is insignificant over 10 5 years., QC 20230307

In this work, the Cu clustering in Fe under irradiation is investigated using experiments, cluster dynamics and atomistic kinetic Monte Carlo (AKMC) simulations. In experiments, cast iron and model FeCu alloy samples were irradiated with 2 MeV electrons for 143 h at 140 °C. The post-irradiation microstructure was characterized using atom probe tomography. Cluster dynamics and AKMC methods were used to sim- ulate the Cu clustering under the same irradiation conditions. Both simulation methods show satisfactory agreement with experiments, lending strength to the validity of the models. Finally, the Cu clustering in spent-fuel repository conditions for 10 5 years at 100 °C was simulated using both methods. The results indicate that potential hardening by Cu clustering is insignificant over 10 5 years., QC 20230307

A combination of density functional theory (DFT) and an efficient calculation method based on Atomistic Kinetic Monte Carlo simulations (AKMC) is used to investigate the interdependence of oxygen (O) and vacancy (v) diffusion in bcc Fe and in dilute iron alloys with the substitutional atoms Y and Ti. Both O and v are considered as mobile while the substitutional atoms are assumed to be immobile. DFT is applied to determine the binding energy between O and v for different distances, the migration barriers for O in the environment of v, and the corresponding barriers of v in the vicinity of O. In agreement with previous work O and v have a very strong binding at the 1st neighbor distance. On the other hand, the calculations show that the Ov pair at the 6th neighbor distance is instable. The newly found simultaneous jumps of both O and v compensate the lack of jump paths that would occur due to this instability. The DFT results are employed to determine the diffusion coefficient of O and v using the AKMC-based calculation method. At first a model system with fixed O and v concentrations is studied. It is found that even a small v content of some ppm can lead to a strong reduction of the O diffusivity. A similar effect is obtained for v diffusion under the influence of O. Furthermore, investigations on the interdependence of O and v diffusion in the first phase of thermal processing of oxide dispersion strengthened iron alloys are performed, and the influence of the substitutional atoms Y and Ti is studied. A simple thermodynamic model is employed to determine the concentration of O, Y, and Ti monomers as well as the total v concentration, for a typical total content of O, Y, and Ti. These results are used in calculations of the diffusion coefficients of O and v. Not only a strong mutual dependence but also a significant influence of Y on O diffusion is found. Finally, O and v diffusivities in a system with an O content close to the thermal solubility are calculated, wh

Iron-based ferritic alloys are used for a plethora of industrial applications. These alloys contain foreign atoms purposely employed to improve certain properties as well as some unwanted impurities introduced during fabrication. Materials properties are decisively influenced by diffusion processes. Very often diffusion cannot be avoided during fabrication and application. Therefore, many efforts are made to understand the underlying atomic-level mechanisms by both experimental and theoretical investigations. In this thesis work a multiscale modelling approach is used to study oxygen and vacancy diffusion in dilute ferritic iron alloys. Due to the extremely low solubility of oxygen the measurement of oxygen diffusion in iron is difficult. Only few experimental data are available. Experimental investigation of vacancy migration is still more complicated. The lack of reliable experimental data is therefore an important motivation for theoretical investigations. Gaining fundamental data on oxygen and vacancy diffusion in dilute iron alloys is essential for many applications. Oxygen plays a crucial role in the corrosion of iron-based alloys. Oxygen and the vacancy are also important in the formation and evolution of Y-Ti-O nanoclusters in oxide dispersion strengthened ferritic Fe-Cr alloys, which are considered as promising candidates for structural materials of future fusion and fission reactors. Furthermore, vacancies are formed during neutron and ion irradiation and their diffusion affects radiation-induced nanostructure formation in ferritic alloys. In the first part of this thesis work, the diffusion of interstitial oxygen under the influence of substitutional atoms or solutes (Al, Si, P, S, Ti, Cr, Mn, Ni, Y, Mo and W) in bcc Fe is investigated by the combination of Density Functional Theory (DFT) and Atomistic Kinetic Monte Carlo (AKMC) simulations. The substitutional atoms are assumed to be immobile because oxygen diffusion is much faster than that of the solute

Iron-based ferritic alloys are used for a plethora of industrial applications. These alloys contain foreign atoms purposely employed to improve certain properties as well as some unwanted impurities introduced during fabrication. Materials properties are decisively influenced by diffusion processes. Very often diffusion cannot be avoided during fabrication and application. Therefore, many efforts are made to understand the underlying atomic-level mechanisms by both experimental and theoretical investigations. In this thesis work a multiscale modelling approach is used to study oxygen and vacancy diffusion in dilute ferritic iron alloys. Due to the extremely low solubility of oxygen the measurement of oxygen diffusion in iron is difficult. Only few experimental data are available. Experimental investigation of vacancy migration is still more complicated. The lack of reliable experimental data is therefore an important motivation for theoretical investigations. Gaining fundamental data on oxygen and vacancy diffusion in dilute iron alloys is essential for many applications. Oxygen plays a crucial role in the corrosion of iron-based alloys. Oxygen and the vacancy are also important in the formation and evolution of Y-Ti-O nanoclusters in oxide dispersion strengthened ferritic Fe-Cr alloys, which are considered as promising candidates for structural materials of future fusion and fission reactors. Furthermore, vacancies are formed during neutron and ion irradiation and their diffusion affects radiation-induced nanostructure formation in ferritic alloys. In the first part of this thesis work, the diffusion of interstitial oxygen under the influence of substitutional atoms or solutes (Al, Si, P, S, Ti, Cr, Mn, Ni, Y, Mo and W) in bcc Fe is investigated by the combination of Density Functional Theory (DFT) and Atomistic Kinetic Monte Carlo (AKMC) simulations. The substitutional atoms are assumed to be immobile because oxygen diffusion is much faster than that of the solute

Iron-based ferritic alloys are used for a plethora of industrial applications. These alloys contain foreign atoms purposely employed to improve certain properties as well as some unwanted impurities introduced during fabrication. Materials properties are decisively influenced by diffusion processes. Very often diffusion cannot be avoided during fabrication and application. Therefore, many efforts are made to understand the underlying atomic-level mechanisms by both experimental and theoretical investigations. In this thesis work a multiscale modelling approach is used to study oxygen and vacancy diffusion in dilute ferritic iron alloys. Due to the extremely low solubility of oxygen the measurement of oxygen diffusion in iron is difficult. Only few experimental data are available. Experimental investigation of vacancy migration is still more complicated. The lack of reliable experimental data is therefore an important motivation for theoretical investigations. Gaining fundamental data on oxygen and vacancy diffusion in dilute iron alloys is essential for many applications. Oxygen plays a crucial role in the corrosion of iron-based alloys. Oxygen and the vacancy are also important in the formation and evolution of Y-Ti-O nanoclusters in oxide dispersion strengthened ferritic Fe-Cr alloys, which are considered as promising candidates for structural materials of future fusion and fission reactors. Furthermore, vacancies are formed during neutron and ion irradiation and their diffusion affects radiation-induced nanostructure formation in ferritic alloys. In the first part of this thesis work, the diffusion of interstitial oxygen under the influence of substitutional atoms or solutes (Al, Si, P, S, Ti, Cr, Mn, Ni, Y, Mo and W) in bcc Fe is investigated by the combination of Density Functional Theory (DFT) and Atomistic Kinetic Monte Carlo (AKMC) simulations. The substitutional atoms are assumed to be immobile because oxygen diffusion is much faster than that of the solute

Iron-based ferritic alloys are used for a plethora of industrial applications. These alloys contain foreign atoms purposely employed to improve certain properties as well as some unwanted impurities introduced during fabrication. Materials properties are decisively influenced by diffusion processes. Very often diffusion cannot be avoided during fabrication and application. Therefore, many efforts are made to understand the underlying atomic-level mechanisms by both experimental and theoretical investigations. In this thesis work a multiscale modelling approach is used to study oxygen and vacancy diffusion in dilute ferritic iron alloys. Due to the extremely low solubility of oxygen the measurement of oxygen diffusion in iron is difficult. Only few experimental data are available. Experimental investigation of vacancy migration is still more complicated. The lack of reliable experimental data is therefore an important motivation for theoretical investigations. Gaining fundamental data on oxygen and vacancy diffusion in dilute iron alloys is essential for many applications. Oxygen plays a crucial role in the corrosion of iron-based alloys. Oxygen and the vacancy are also important in the formation and evolution of Y-Ti-O nanoclusters in oxide dispersion strengthened ferritic Fe-Cr alloys, which are considered as promising candidates for structural materials of future fusion and fission reactors. Furthermore, vacancies are formed during neutron and ion irradiation and their diffusion affects radiation-induced nanostructure formation in ferritic alloys. In the first part of this thesis work, the diffusion of interstitial oxygen under the influence of substitutional atoms or solutes (Al, Si, P, S, Ti, Cr, Mn, Ni, Y, Mo and W) in bcc Fe is investigated by the combination of Density Functional Theory (DFT) and Atomistic Kinetic Monte Carlo (AKMC) simulations. The substitutional atoms are assumed to be immobile because oxygen diffusion is much faster than that of the solute

The Invar anomaly is one of the most fascinating phenomena observed in magnetically ordered materials. Invariant thermal expansion and elastic properties have attracted substantial scientific attention and led to important technological solutions. By studying planar faults in the high-temperature magnetically disordered state of Ni1-cFec, here we disclose a completely different anomaly. An invariant plastic deformation mechanism is characterized by an unchanged stacking fault energy with temperature within wide concentration and temperature ranges. This anomaly emerges from the competing stability between the face-centered cubic and hexagonal close-packed structures and occurs in other paramagnetic or nonmagnetic systems whenever the structural balance exists. The present findings create a platform for tailoring high-temperature properties of technologically relevant materials toward plastic stability at elevated temperatures.

The Invar anomaly is one of the most fascinating phenomena observed in magnetically ordered materials. Invariant thermal expansion and elastic properties have attracted substantial scientific attention and led to important technological solutions. By studying planar faults in the high-temperature magnetically disordered state of Ni1-cFec, here we disclose a completely different anomaly. An invariant plastic deformation mechanism is characterized by an unchanged stacking fault energy with temperature within wide concentration and temperature ranges. This anomaly emerges from the competing stability between the face-centered cubic and hexagonal close-packed structures and occurs in other paramagnetic or nonmagnetic systems whenever the structural balance exists. The present findings create a platform for tailoring high-temperature properties of technologically relevant materials toward plastic stability at elevated temperatures., QC 20210526

Chromium–iron (CrFe) binary alloys have recently been proposed to serve as the “inert” anode for molten oxide electrolysis (MOE). Herein, the effects of anodic polarization on physical and functional properties of CrFe anodes in the corrosive environment of MOE are studied via empirical observations and theoretical calculations. The findings indicate that the alloys form an inner chromia–alumina solid-solution covered by an MgCr2O4 spinel layer. A survey into the electrical properties of the detected oxides suggests that the layered oxide scale function as an efficient conductor of electricity at elevated temperature. The formation mechanism of the oxides is also investigated.

Diplomová práce je rozdělena na dvě hlavní části, praktickou a teoretickou. Praktická část prezentuje komplexní restaurátorský zásah na renesančním štukovém epitafu Jana Hodějovského z Hodějova a jeho rodiny umístěnému na severní zdi v kostele sv. Jana Křtitele v Českém Rudolci. Toto dílo bylo vytvořeno neznámým autorem roku 1582. Práce dokumentuje celý restaurátorský průzkum, na jehož základě byla zvolena koncepce restaurátorského zásahu. Dokument mapuje veškeré postupy a provedené zásahy během restaurátorského zásahu. Teoretická část se v úvodu zabývá seznámením se s materiály a problematikou koroze kovů. V úvodu je zaměřena na možnosti čištění korozních produktů ze sádrového povrchu. Pozornost byla zaměřena na shromáždění všech možných způsobů čištění za pomoci chemických látek, zatímco druhá, experimentální část, představuje zkoušky čištění ze zkušebních vzorků. Výsledky byly ověřeny na skutečném sádrovém díle se znečištěním korozními produkty., The diploma thesis is divided into two main parts, practical and theoretical. The practical part presents a comprehensive restoration intervention on the Renaissance stucco epitaph of Jan Hodějovský of Hodějov and his family located on the north wall in the Church of St. John the Baptist, Český Rudolec. This work was created by an unknown artist in 1582. The paper documents the entire restoration survey, which laid the basis for the restoration treatment concept. Besides, this part maps all the procedures and interventions performed during the restoration intervention. The theoretical part deals with the introduction to materials and corrosion of metals. The introduction focuses on the options of cleaning corrosion products from gypsum surfaces. The aim was to collect all possible cleaning methods with the help of chemicals. The second experimental part presents cleaning tests performed on plaster specimens; the data gained in the testing were verified on a real plaster artwork affected by corrosion of iron reinforcement, Fakulta restaurování, Studentka formou prezentace představila téma a náplň diplomové práce. Pohotově reagovala na dotazy komise, přičemž důsledně dodržovala smysl zadávaných otázek a odpovědi byly konkrétní a vyčerpávající. V případě praktické části dostatečně ozřejmila svůj podíl na restaurování artefaktu i ozřejmila použité metody, v rámci obhajoby teoretické části bylo ozřejmění zadání logické a otázky byly zodpovězeny přiměřeně., Dokončená práce s úspěšnou obhajobou

This paper is an invited submission to IJMC selected from presentations at the 2nd Carl Loper 2019 Cast Iron Symposium held September 30 to October 1, 2019, in Bilbao, Spain.

In this paper, we aim at characterizing three different cast iron alloys and their microstructural features, namely lamellar, compacted and nodular graphite iron. The characterization of microscopic features is essential for the development of methods to optimize the behavior of cast iron alloys; e.g. maximize thermal dissipation and/or maximize ductility while maintaining strength. The variation of these properties is commonly analyzed by metallography on two-dimensional representations of the alloy. However, more precise estimates of the morphologies and material characteristics are obtained by three-dimensional reconstruction of microstructures. The use of X-ray microtomography provides an excellent tool to generate high resolution threedimensional microstructure images. The characteristics of the graphite constituent in the microstructure, including the size, shape and connectivity, were analyzed for the different cast iron alloys. It was observed that the lamellar and compacted graphite iron alloys have relatively large connected graphite morphologies, as opposed to ductile iron where the graphite is present as nodules. The results of the characterization for the different alloys were ultimately used to generate finite element models., CC BY 4.0

In this paper, we aim at characterizing three different cast iron alloys and their microstructural features, namely lamellar, compacted and nodular graphite iron. The characterization of microscopic features is essential for the development of methods to optimize the behavior of cast iron alloys; e.g. maximize thermal dissipation and/or maximize ductility while maintaining strength. The variation of these properties is commonly analyzed by metallography on two-dimensional representations of the alloy. However, more precise estimates of the morphologies and material characteristics are obtained by three-dimensional reconstruction of microstructures. The use of X-ray microtomography provides an excellent tool to generate high resolution threedimensional microstructure images. The characteristics of the graphite constituent in the microstructure, including the size, shape and connectivity, were analyzed for the different cast iron alloys. It was observed that the lamellar and compacted graphite iron alloys have relatively large connected graphite morphologies, as opposed to ductile iron where the graphite is present as nodules. The results of the characterization for the different alloys were ultimately used to generate finite element models., CC BY 4.0

In this paper, we aim at characterizing three different cast iron alloys and their microstructural features, namely lamellar, compacted and nodular graphite iron. The characterization of microscopic features is essential for the development of methods to optimize the behavior of cast iron alloys; e.g. maximize thermal dissipation and/or maximize ductility while maintaining strength. The variation of these properties is commonly analyzed by metallography on two-dimensional representations of the alloy. However, more precise estimates of the morphologies and material characteristics are obtained by three-dimensional reconstruction of microstructures. The use of X-ray microtomography provides an excellent tool to generate high resolution threedimensional microstructure images. The characteristics of the graphite constituent in the microstructure, including the size, shape and connectivity, were analyzed for the different cast iron alloys. It was observed that the lamellar and compacted graphite iron alloys have relatively large connected graphite morphologies, as opposed to ductile iron where the graphite is present as nodules. The results of the characterization for the different alloys were ultimately used to generate finite element models., CC BY 4.0

In this paper, we aim at characterizing three different cast iron alloys and their microstructural features, namely lamellar, compacted and nodular graphite iron. The characterization of microscopic features is essential for the development of methods to optimize the behavior of cast iron alloys; e.g. maximize thermal dissipation and/or maximize ductility while maintaining strength. The variation of these properties is commonly analyzed by metallography on two-dimensional representations of the alloy. However, more precise estimates of the morphologies and material characteristics are obtained by three-dimensional reconstruction of microstructures. The use of X-ray microtomography provides an excellent tool to generate high resolution threedimensional microstructure images. The characteristics of the graphite constituent in the microstructure, including the size, shape and connectivity, were analyzed for the different cast iron alloys. It was observed that the lamellar and compacted graphite iron alloys have relatively large connected graphite morphologies, as opposed to ductile iron where the graphite is present as nodules. The results of the characterization for the different alloys were ultimately used to generate finite element models., CC BY 4.0

In this paper, we aim at characterizing three different cast iron alloys and their microstructural features, namely lamellar, compacted and nodular graphite iron. The characterization of microscopic features is essential for the development of methods to optimize the behavior of cast iron alloys; e.g. maximize thermal dissipation and/or maximize ductility while maintaining strength. The variation of these properties is commonly analyzed by metallography on two-dimensional representations of the alloy. However, more precise estimates of the morphologies and material characteristics are obtained by three-dimensional reconstruction of microstructures. The use of X-ray microtomography provides an excellent tool to generate high resolution threedimensional microstructure images. The characteristics of the graphite constituent in the microstructure, including the size, shape and connectivity, were analyzed for the different cast iron alloys. It was observed that the lamellar and compacted graphite iron alloys have relatively large connected graphite morphologies, as opposed to ductile iron where the graphite is present as nodules. The results of the characterization for the different alloys were ultimately used to generate finite element models.

In this paper, we aim at characterizing three different cast iron alloys and their microstructural features, namely lamellar, compacted and nodular graphite iron. The characterization of microscopic features is essential for the development of methods to optimize the behavior of cast iron alloys; e.g. maximize thermal dissipation and/or maximize ductility while maintaining strength. The variation of these properties is commonly analyzed by metallography on two-dimensional representations of the alloy. However, more precise estimates of the morphologies and material characteristics are obtained by three-dimensional reconstruction of microstructures. The use of X-ray microtomography provides an excellent tool to generate high resolution threedimensional microstructure images. The characteristics of the graphite constituent in the microstructure, including the size, shape and connectivity, were analyzed for the different cast iron alloys. It was observed that the lamellar and compacted graphite iron alloys have relatively large connected graphite morphologies, as opposed to ductile iron where the graphite is present as nodules. The results of the characterization for the different alloys were ultimately used to generate finite element models., CC BY 4.0

Purpose. It is of interest to investigate the relationship between secondary hardening and microstresses in the crystal lattice on the tempering temperature of iron alloys doped by the principle of high-speed steels after complex chemical-thermal treatment. It is necessary to identify structural transformations in a complex treated alloy of type 20P18 after the final heat treatment (quenching and tempering) by electron microscopic. It is of interest to study the regularities of the formation of preallocation zones of the Guinier−Preston type in high-alloyed iron alloys after the final thermal treatment. Methodology. The materials for investigation was the cast alloy of type 20P18 made on the basis of standard P18 steel with the addition of carbon to ~2 %. The degree of perfection of the crystal lattice of the 20P18 alloy was evaluated after the implementation of complex chemical-thermal treatment (decarburization + carburization) and tempering at various parameters. Methods of research − electron microscopy and optical microscopy. Results. It was found that the maximum lattice tension and high microhardness for the type 20P18 alloy correspond to tempering at temperatures of 550...560 °C. It is shown that fine-dispersed carbides of the M3C type are distinguished in the diffusion layer after tempering, which are also characteristic of standard high-speed steel, but in a larger quantity. The maximum of the secondary hardness of high-alloyed iron alloys corresponds to the stage of formation of the Guinie−Preston preallocation zones, which corresponds to tempering at temperatures of 550...560 °C was established. Originality. It is established that formation zones of the Guinier−Preston in the process of tempering to secondary hardness contribute to the distortion of the crystal lattice of the solid solution. Practical value. The using of the obtained results will allow more flexible control over the final structure of specific products, and, consequently, successfully s

There is a desperate need for alternative and renewable energy sources to meet the raising demands of our global technological society. Magnetic materials are uniquely poised to address many of the energy demands including in sectors such as energy generation and transmission, transportation, refrigeration, and manufacturing. Improving material properties for these applications would result in enormous impacts to industry in the form of reduced energy costs and reduced greenhouse gas emissions. There is a desperate need for alternative and renewable energy sources to meet the raising demands of our global technological society. Magnetic materials are uniquely poised to address many of the energy demands including in sectors such as energy generation and transmission, transportation, refrigeration, and manufacturing. Improving material properties for these applications would result in enormous impacts to industry in the form of reduced energy costs and reduced greenhouse gas emissions. Nanostructured materials present a promising path forward for improving these magnetic properties. Magnetocrystalline anisotropy has been used to describe how grains at the nanoscale effect coercivity. However, there remains a gap in knowledge for describing how nanoscale features effect other critical magnetic properties such as permeability, domain wall movement, and frequency dependence. Additionally, the fundamental mechanisms by which these properties depend on microstructures are unknown. Probing microstructure, chemistry, and magnetic properties at the nanoscale has proven to be challenging, because of the convolution of magnetic and structural information in common nanoscale characterization techniques. Understanding of how magnetic domains interact within complex nanostructured features including many types of defect interactions is critical for engineering materials that take advantage of these properties. Here several amorphous/nanocrystalline Fe based alloys with a rich var

There is a desperate need for alternative and renewable energy sources to meet the raising demands of our global technological society. Magnetic materials are uniquely poised to address many of the energy demands including in sectors such as energy generation and transmission, transportation, refrigeration, and manufacturing. Improving material properties for these applications would result in enormous impacts to industry in the form of reduced energy costs and reduced greenhouse gas emissions. There is a desperate need for alternative and renewable energy sources to meet the raising demands of our global technological society. Magnetic materials are uniquely poised to address many of the energy demands including in sectors such as energy generation and transmission, transportation, refrigeration, and manufacturing. Improving material properties for these applications would result in enormous impacts to industry in the form of reduced energy costs and reduced greenhouse gas emissions. Nanostructured materials present a promising path forward for improving these magnetic properties. Magnetocrystalline anisotropy has been used to describe how grains at the nanoscale effect coercivity. However, there remains a gap in knowledge for describing how nanoscale features effect other critical magnetic properties such as permeability, domain wall movement, and frequency dependence. Additionally, the fundamental mechanisms by which these properties depend on microstructures are unknown. Probing microstructure, chemistry, and magnetic properties at the nanoscale has proven to be challenging, because of the convolution of magnetic and structural information in common nanoscale characterization techniques. Understanding of how magnetic domains interact within complex nanostructured features including many types of defect interactions is critical for engineering materials that take advantage of these properties. Here several amorphous/nanocrystalline Fe based alloys with a rich var

We present a systematic analysis, based on ab initio calculations, of concentrated solute arrangements and precipitate phases in Fe-based alloys. The input data for our analysis are the calculated formation and interaction energies of point defects in the iron matrix, as well as the energies of ordered compounds that represent end-members in the 4-sublattice compound energy model of a multicomponent solid solution of Mg, Al, Si, P, S, Mn, Ni, and Cu elements and also vacancies in bcc Fe. The list of compounds also includes crystal structures obtained by geometric relaxation of the end-member compounds that in the cubic structure show weak mechanical instabilities (negative elastic constants) and also the G-phase Mn-6(Ni,Fe)(16)(Si,P)(7) having a complex cubic structure. A database of calculated thermodynamic properties (crystal structure, molar volume, enthalpy of formation, and elastic constants) of the most stable late-blooming-phase candidates is thus obtained. The results of this ab initio based theoretical analysis compare well with the recent experimental observations and predictions of thermodynamic calculations employing Calphad methodology., QC 20180919

Growing concerns over the use of cobalt as binder for WC-based hardmetals has directed research efforts towards finding a suitable alternative binder offering comparable or even superior properties than those found in WC–Co hardmetals. Complete substitution of cobalt by iron alloys has been extensively explored in several studies with significant improvements in mechanical properties of WC bonded with Fe alloys when carbon content addition is strictly controlled in powder composition. Asides from the commonly studied hardness and fracture toughness properties, transverse rupture strength property of this composites has also been observed to hold future promise with further development in the microstructural parameters such as porosity during sintering. This article reviews the progress in the mechanical properties of WC–Fe alloys hardmetals.

Growing concerns over the use of cobalt as binder for WC-based hardmetals has directed research efforts towards finding a suitable alternative binder offering comparable or even superior properties than those found in WC–Co hardmetals. Complete substitution of cobalt by iron alloys has been extensively explored in several studies with significant improvements in mechanical properties of WC bonded with Fe alloys when carbon content addition is strictly controlled in powder composition. Asides from the commonly studied hardness and fracture toughness properties, transverse rupture strength property of this composites has also been observed to hold future promise with further development in the microstructural parameters such as porosity during sintering. This article reviews the progress in the mechanical properties of WC–Fe alloys hardmetals.

A multiscale approach including Density Functional Theory (DFT) and Atomistic Kinetic Monte Carlo (AKMC) simulations is applied to investigate the diffusion of interstitial oxygen atoms in bcc Fe under the influence of substitutional foreign atoms (Al, Si, P, S, Ti, Cr, Mn, Ni, Y, Mo, W). The substitutional atoms can be assumed to be immobile since their diffusion coefficient is much smaller than that of oxygen. At first jumps of oxygen in pure bcc Fe, between first-, second-, and third-neighbor octahedral interstitial sites are investigated. It is found that the first-neighbor jump is most relevant, with the tetrahedral site as the saddle point. The second-neighbor jump consists of two consecutive first-neighbor jumps. The barrier for a direct third-neighbor jump is too high to be significant for the diffusion process. In the presence of substitutional atoms the most important migration paths are first-neighbor jumps between modified octahedral sites with modified tetrahedral sites as saddle points. Calculations show that Si, P, Ni, Mo and W cause some modifications of the migration barriers of oxygen and their interaction with O is mainly repulsive. Al, Cr and Mn have a significant influence on the barriers and they exhibit strong attractive interactions with O. The most important modification of the barriers is found for S, Ti, and Y where deep attractive states exist. Based on the migration energies obtained by DFT, AKMC simulations on a rigid lattice are employed to determine the diffusion coefficient of oxygen in a dilute iron alloy containing the different substitutional atoms. It is found that Si, P, Ni, Mo, and W have almost no influence on the diffusivity of O, i.e. it is nearly identical to that in pure bcc Fe. The presence of Al, Cr, Mn, S, Ti, and Y causes a significant reduction of the mobility of oxygen. In these cases the temperature dependence of the oxygen diffusion coefficient shows considerable deviations from an Arrhenius law and other peculiari

Variants of initiation of growth of crystals of a-martensite by couplcs of clastic waves propagating in direc­tions 〈001〉γ and 〈110〉γ in singles crystals of Fe3 INi are suggested. The dynamic theory is used to show that the expected orientations of habit planes {110}γ, {001}γ and {559}γ differ from the typical {31015}γ. Possible features of tetragonality of martensite crystals arc discussed. The power of the sources of ultrasound required for initiation of γ - α martensitic transformation is estimated. © 2016 Springer Science + Business Media New York.

The objective of this investigation was to set down (on the basis of the results obtained by the examination of white cast iron alloys with different contents of alloying elements) a correlation between chemical composition and microstructure, on one hand, and the properties relevant for this group of materials, i.e., wear resistance and fracture toughness, on the other. Experimental results indicate that the volume fraction of the eutectic carbide phase (M3C or M7C3) have an important influence on the wear resistance of white iron alloys under low-stress abrasion conditions. Besides, the martensitic or martensite-austenitic matrix microstructure more adequately reinforced the eutectic carbides, minimizing cracking and removal during wear, than did the austenitic matrix. The secondary carbides which precipitate in the matrix regions of high chromium iron also influence the abrasion behaviour. The results of fracture toughness tests show that the dynamic fracture toughness in white irons is determined mainly by the properties of the matrix. The high chromium iron containing 1.19 wt% V in the as-cast condition, showed the greater fracture toughness when compared to other experimental alloys. The higher toughness was attributed to strengthening during fracture, since very fine secondary carbide particles were present mainly in an austenitic matrix.

The objective of this investigation was to set down (on the basis of the results obtained by the examination of white cast iron alloys with different contents of alloying elements) a correlation between chemical composition and microstructure, on one hand, and the properties relevant for this group of materials, i.e., wear resistance and fracture toughness, on the other. Experimental results indicate that the volume fraction of the eutectic carbide phase (M3C or M7C3) have an important influence on the wear resistance of white iron alloys under low-stress abrasion conditions. Besides, the martensitic or martensite-austenitic matrix microstructure more adequately reinforced the eutectic carbides, minimizing cracking and removal during wear, than did the austenitic matrix. The secondary carbides which precipitate in the matrix regions of high chromium iron also influence the abrasion behaviour. The results of fracture toughness tests show that the dynamic fracture toughness in white irons is determined mainly by the properties of the matrix. The high chromium iron containing 1.19 wt% V in the as-cast condition, showed the greater fracture toughness when compared to other experimental alloys. The higher toughness was attributed to strengthening during fracture, since very fine secondary carbide particles were present mainly in an austenitic matrix.

Versions are provided for alpha-martensite rod-shaped crystal initiation by three orthogonal longitudinal elastic waves propagating in orthogonal directions of the types aOE (c) 001 >(gamma) and aOE (c) 110 >(gamma) in Fe - 31% Ni single crystals. The probability is considered of direct initiation by Bain-type deformation waves. It is demonstrated within the scope of dynamic theory that the anticipated orientation of rod-like crystals is close to aOE (c) 111 >(gamma) or to aOE (c) 905 >(gamma). Possible features of martensite crystal tetragonality are discussed. Ultrasound source power required for initiating martensitic transformation is determined., Work was carried out with financial support of the RFFI (project number 14-08-00734).

Versions are provided for alpha-martensite rod-shaped crystal initiation by three orthogonal longitudinal elastic waves propagating in orthogonal directions of the types aOE (c) 001 >(gamma) and aOE (c) 110 >(gamma) in Fe - 31% Ni single crystals. The probability is considered of direct initiation by Bain-type deformation waves. It is demonstrated within the scope of dynamic theory that the anticipated orientation of rod-like crystals is close to aOE (c) 111 >(gamma) or to aOE (c) 905 >(gamma). Possible features of martensite crystal tetragonality are discussed. Ultrasound source power required for initiating martensitic transformation is determined., Work was carried out with financial support of the RFFI (project number 14-08-00734).

As a part of ThermoLab project, the thermophysical properties of industrially important iron alloys were measured. In this paper, the measurement results of the differential scanning calorimetry (DSC), specific heat capacity, thermal diffusivity, surface tension and viscosity of one Fe-Cr and of a low oxygen eutectoid manganese steel are reported. In addition to the ground based experiments, parabolic flights (microgravity) experiments with a non-contact electromagnetic levitation device were employed for surface tension and viscosity measurements., QC 20100525

As a part of ThermoLab project, the thermophysicalproperties of industrially important iron alloys weremeasured. In this paper, the measurement results of thedifferential scanning calorimetry (DSC), specific heatcapacity, thermal diffusivity, surface tension andviscosity of one Fe-Cr and of a low oxygen eutectoidmanganese steel are reported. In addition to the groundbased experiments, parabolic flights (microgravity)experiments with a non-contact electromagneticlevitation device were employed for surface tension andviscosity measurements.

The static and low cycle fatigue properties of four pearlitic grey iron alloys intended for brake discs are investigated. The effect of alloying a base composition with 0.1 wt% and 0.3 wt% niobium is compared to a 0.3 wt% addition of the more conventional alloying element molybdenum. The results show that the static properties remain unaffected for an Nb content of 0.1 wt% while an addition of 0.3 wt% Nb or 0.3 wt% Mo increases the strength compared to the base alloy without Nb and Mo. The fatigue life on the other hand remains more or less unaffected by the alloying, although the stress levels are substantially higher for the compositions with 0.3 wt% Mo or 0.3 wt% Nb. Thus, the experiments show that graphite is very important for the low cycle fatigue life. It is also seen that crack propagation controls more than 90% of the life. Full scale brake dynamometer crack tests also gave a similar fatigue life of the different brake disc alloys independent of the composition.

The objective of the FP6 Perfect Project was to develop a first example of integrated multiscale computational models, capable of describing the effects of irradiation in nuclear reactor components, namely vessel and internals. The use of ab initio techniques to study, in the most reliable way currently possible, atomic-level interactions between species and defects, and the transfer of this knowledge to interatomic potentials, of use for large scale dynamic simulations, lie at the core of this effort. The target materials of the Project were bainitic steels (vessel) and austenitic steels (internals), i.e. iron alloys. In this article, the advances made within the Project in the understanding of defect properties in Fe alloys, by means of ab initio calculations, and in the development of interatomic potentials for Fe and Fe alloys are overviewed, thereby providing a reference basis for further progress in the field. Emphasis is put in showing how the produced data have enhanced our level of understanding of microstructural processes occurring under irradiation in model alloys and steels used in existing nuclear power plants., QC 20120124

U radu su prikazani rezultati istraživanja stanja industrije proizvodnje i prerade legura železa u tečnom stanju u Srbiji u poslednjoj deceniji prošlog veka. Istraživanja su obuhvatila kapacitete livnica, tehnološke postupke livenja, stanje opreme, kadrove i uposlenost kapaciteta. Nakon analize prikupljenih podataka predloženi su strateški ciljevi razvoja za naredni period., The results of investigation on the situation in production and processing industry of iron alloys in liquid state in Serbia, in the last century latter decade, is presented in thi paper. The investigations encompassed the following: foundry capacities, foundry technologies used, the state of equipment, personnel and capacities employment. After collected data analysis, the strategic goals in development are suggested for the next period.

The topic of this thesis covers a broad range of phenomena through three significant phase transformations in iron alloys, being solidification, delta-ferrite to austenite and austenite decomposition. An appreciation of the links between these diverse transformations is necessary to understand the purpose of the present study. One such link is the concept of morphological stability of interphase boundaries during transformations. Another link between the three phase transformation is the lack of studies conducted utilising in-situ, real-time observations of phenomena. With the advent of high temperature laser scanning confocal microscopy, it is now possible to overcome previous experimental difficulties associated with resolving images at high temperature. Therefore, experimental analysis can be conducted into not just the morphology of transformation interfaces, but into a range of additional phenomena such as the development of recovery structures and growth kinetics. For the studies conducted utilising LSCM it was necessary, due to the novelty of the technique, to establish both a frame of reference for interpreting observations, and to characterise the influence of the free surface on the observations. In regard to the nexus between events on the free surface and in the bulk, endeavours were undertaken to establish phenomena that are affected by the free surface and those that are not. Serial sectioning analysis has led to the conclusion that solid-state phase transformations of delta-ferrite to austenite and austenite decomposition do show a correlation between events on the free surface and those in the bulk. Phenomena that do not exhibit a nexus between events on the free surface and in the bulk were identified. These were the pinning of grain boundaries by surface defects, anomalous massive phase transformations and precipitation of non-metallic particles. The aim of the experimental studies into the relationship between crystallographic orientation and the

The topic of this thesis covers a broad range of phenomena through three significant phase transformations in iron alloys, being solidification, delta-ferrite to austenite and austenite decomposition. An appreciation of the links between these diverse transformations is necessary to understand the purpose of the present study. One such link is the concept of morphological stability of interphase boundaries during transformations. Another link between the three phase transformation is the lack of studies conducted utilising in-situ, real-time observations of phenomena. With the advent of high temperature laser scanning confocal microscopy, it is now possible to overcome previous experimental difficulties associated with resolving images at high temperature. Therefore, experimental analysis can be conducted into not just the morphology of transformation interfaces, but into a range of additional phenomena such as the development of recovery structures and growth kinetics. For the studies conducted utilising LSCM it was necessary, due to the novelty of the technique, to establish both a frame of reference for interpreting observations, and to characterise the influence of the free surface on the observations. In regard to the nexus between events on the free surface and in the bulk, endeavours were undertaken to establish phenomena that are affected by the free surface and those that are not. Serial sectioning analysis has led to the conclusion that solid-state phase transformations of delta-ferrite to austenite and austenite decomposition do show a correlation between events on the free surface and those in the bulk. Phenomena that do not exhibit a nexus between events on the free surface and in the bulk were identified. These were the pinning of grain boundaries by surface defects, anomalous massive phase transformations and precipitation of non-metallic particles. The aim of the experimental studies into the relationship between crystallographic orientation and the

The topic of this thesis covers a broad range of phenomena through three significant phase transformations in iron alloys, being solidification, delta-ferrite to austenite and austenite decomposition. An appreciation of the links between these diverse transformations is necessary to understand the purpose of the present study. One such link is the concept of morphological stability of interphase boundaries during transformations. Another link between the three phase transformation is the lack of studies conducted utilising in-situ, real-time observations of phenomena. With the advent of high temperature laser scanning confocal microscopy, it is now possible to overcome previous experimental difficulties associated with resolving images at high temperature. Therefore, experimental analysis can be conducted into not just the morphology of transformation interfaces, but into a range of additional phenomena such as the development of recovery structures and growth kinetics. For the studies conducted utilising LSCM it was necessary, due to the novelty of the technique, to establish both a frame of reference for interpreting observations, and to characterise the influence of the free surface on the observations. In regard to the nexus between events on the free surface and in the bulk, endeavours were undertaken to establish phenomena that are affected by the free surface and those that are not. Serial sectioning analysis has led to the conclusion that solid-state phase transformations of delta-ferrite to austenite and austenite decomposition do show a correlation between events on the free surface and those in the bulk. Phenomena that do not exhibit a nexus between events on the free surface and in the bulk were identified. These were the pinning of grain boundaries by surface defects, anomalous massive phase transformations and precipitation of non-metallic particles. The aim of the experimental studies into the relationship between crystallographic orientation and the

For better understanding of the influence of the deleterious elements on the neutron embrittlement of reactor pressure vessel steels, the microstructural evolution due to neutron irradiation was investigated by SANS experiments at ternary iron alloys with different contents of copper and phosphorus. In every case irradiation produced nanoscaled inhomogeneities. The volume fraction of the inhomogeneities incrases with the copper content but not with the phosphorus content. Surprisingly, the high-pure alloy shows a relatively high irradiation effect. The irradiation defects vary in type and kinetic of evolution for the different alloys.

For better understanding of the influence of the deleterious elements on the neutron embrittlement of reactor pressure vessel steels, the microstructural evolution due to neutron irradiation was investigated by SANS experiments at ternary iron alloys with different contents of copper and phosphorus. In every case irradiation produced nanoscaled inhomogeneities. The volume fraction of the inhomogeneities incrases with the copper content but not with the phosphorus content. Surprisingly, the high-pure alloy shows a relatively high irradiation effect. The irradiation defects vary in type and kinetic of evolution for the different alloys.

For better understanding of the influence of the deleterious elements on the neutron embrittlement of reactor pressure vessel steels, the microstructural evolution due to neutron irradiation was investigated by SANS experiments at ternary iron alloys with different contents of copper and phosphorus. In every case irradiation produced nanoscaled inhomogeneities. The volume fraction of the inhomogeneities incrases with the copper content but not with the phosphorus content. Surprisingly, the high-pure alloy shows a relatively high irradiation effect. The irradiation defects vary in type and kinetic of evolution for the different alloys.

Irradiation of reactor pressure vessel (RPV) steels induces a degradation of the mechanical properties caused by the formation of nano-scale defect-solute clusters. Impurity Cu plays the major role in cluster formation, whereas the effect of the alloying element Ni depends on the Cu level and is not yet well understood. The present experiment was devoted to the Ni effect. The SANS results for a Fe-3%Ni alloy, pure Fe and model alloys were reported.

Irradiation of reactor pressure vessel (RPV) steels induces a degradation of the mechanical properties caused by the formation of nano-scale defect-solute clusters. Impurity Cu plays the major role in cluster formation, whereas the effect of the alloying element Ni depends on the Cu level and is not yet well understood. The present experiment was devoted to the Ni effect. The SANS results for a Fe-3%Ni alloy, pure Fe and model alloys were reported.

Inelastic neutron scattering (INS) and nuclear-resonant inelastic x-ray scattering (NRIXS) were used to measure phonon spectra of FeV as a B2- ordered compound and as a bcc solid solution. Contrary to the behavior of ordering alloys studied to date, the phonons in the B2-ordered phase are softer than in the solid solution. Ordering increases the vibrational entropy, which stabilizes the ordered phase to higher temperatures. Ab initio calculations show that the number of electronic states at the Fermi level increases upon ordering, enhancing the screening between ions, and reducing the interatomic force constants. The effect of screening is larger at the V atomic sites than at the Fe atomic sites. The phonon spectra of Au-rich alloys of fcc Au-Fe were also measured. The main effect on the vibrational entropy of alloying comes from a stiffening of the Au partial phonon density of states (DOS) with Fe concentration that increases the miscibility gap temperature. The magnitude of the effect is non- linear and it is reduced at higher Fe concentrations. Force constants were calculated for several compositions and show a local stiffening of Au–Au bonds close to Fe atoms, but Au–Au bonds that are farther away do not show this effect. Phonon DOS curves calculated from the force constants reproduced the experimental trends. The Au–Fe bond is soft and favors ordering, but a charge transfer from the Fe to the Au atoms stiffens the Au–Au bonds enough to favor unmixing. The stiffening is attributed to two main effects comparable in magnitude: an increase in electron density in the free-electron-like states, and stronger sd-hybridization. INS and NRIXS measurements were performed at elevated temperatures on B2-ordered FeTi and NRIXS measurements were performed at high pressures. The high-pressure behavior is quasi- harmonic. The softening of the phonon DOS curves with temperature is strongly nonharmonic. Calculations of the force constants and Born-von Karman fits

Inelastic neutron scattering (INS) and nuclear-resonant inelastic x-ray scattering (NRIXS) were used to measure phonon spectra of FeV as a B2- ordered compound and as a bcc solid solution. Contrary to the behavior of ordering alloys studied to date, the phonons in the B2-ordered phase are softer than in the solid solution. Ordering increases the vibrational entropy, which stabilizes the ordered phase to higher temperatures. Ab initio calculations show that the number of electronic states at the Fermi level increases upon ordering, enhancing the screening between ions, and reducing the interatomic force constants. The effect of screening is larger at the V atomic sites than at the Fe atomic sites. The phonon spectra of Au-rich alloys of fcc Au-Fe were also measured. The main effect on the vibrational entropy of alloying comes from a stiffening of the Au partial phonon density of states (DOS) with Fe concentration that increases the miscibility gap temperature. The magnitude of the effect is non- linear and it is reduced at higher Fe concentrations. Force constants were calculated for several compositions and show a local stiffening of Au–Au bonds close to Fe atoms, but Au–Au bonds that are farther away do not show this effect. Phonon DOS curves calculated from the force constants reproduced the experimental trends. The Au–Fe bond is soft and favors ordering, but a charge transfer from the Fe to the Au atoms stiffens the Au–Au bonds enough to favor unmixing. The stiffening is attributed to two main effects comparable in magnitude: an increase in electron density in the free-electron-like states, and stronger sd-hybridization. INS and NRIXS measurements were performed at elevated temperatures on B2-ordered FeTi and NRIXS measurements were performed at high pressures. The high-pressure behavior is quasi- harmonic. The softening of the phonon DOS curves with temperature is strongly nonharmonic. Calculations of the force constants and Born-von Karman fits