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Abstract Iron alloys, including steels and magnetic functional materials, are widely used in capital construction, manufacturing, electromagnetic technology, etc. However, they face the long-standing challenge of high coefficient of thermal expansion (CTE), limiting the applications in high-precision fields. This work proposes a strategy involving the in-situ formation of a nano-scale lamellar/labyrinthine negative thermal expansion (NTE) phase within the iron matrix to tackle this problem. For example, a model alloy, Fe-Zr10-Nb6, was synthesized and its CTE is reduced to approximately half of the iron matrix. Meanwhile, the alloy possesses a strength-plasticity combination of 1.5 GPa (compressive strength) and 17.5% (ultimate strain), which outperforms other low thermal expansion (LTE) metallic materials. The magnetovolume effect of the NTE phase is deemed to counteract the positive thermal expansion in iron. The high stress-carrying hard NTE phase and the tough matrix synergistically contribute to the high mechanical properties. The interaction between the slip of lamellar microstructure and the slip-hindering of labyrinthine microstructure further enhances the strength-plasticity combination. This work shows the promise of offering a method to produce LTE iron alloys with high mechanical properties.

Classification of cast iron alloys based on graphite morphology plays a crucial role in materials science and engineering. Traditionally, this classification has relied on visual analysis, a method that is not only time‐consuming but also suffers from subjectivity, leading to inconsistencies. This study introduces a novel approach utilizing convolutional neural networks—MobileNet for image classification and U‐Net for semantic segmentation—to automate the classification process of cast iron alloys. A significant challenge in this domain is the limited availability of diverse and comprehensive datasets necessary for training effective machine learning models. This is addressed by generating a synthetic dataset, creating a rich collection of 2400 pure and 1500 mixed images based on the ISO 945‐1:2019 standard. This ensures a robust training process, enhancing the model's ability to generalize across various morphologies of graphite particles. The findings showcase a remarkable accuracy in classifying cast iron alloys (achieving an overall accuracy of 98.9 ± 0.4%—and exceeding 97% for all six classes—for classification of pure images and ranging between 84% and 93% for semantic segmentation of mixed images) and also demonstrate the model's ability to consistently identify and graphite morphology with a level of precision and speed unattainable through manual methods. [ABSTRACT FROM AUTHOR]

Copyright of Nonferrous Metals (Extractive Metallurgy) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The surface segregation process and its influence on high-temperature corrosion of five alloys—Fe0.95Al0.05, Fe0.95V0.05, Fe0.90Al0.05V0.05, Fe0.95Ti0.05 and Fe0.95Ge0.05—were studied using X-ray photoelectron spectroscopy (XPS) and 57Fe Transmission Mössbauer Spectroscopy (TMS). To prepare the alloys with the highest surface concentration of solutes, the samples were annealed at elevated temperatures to induce the surface segregation process. After that, they were exposed to air at 870 K for 1 and 5 h. It was found that the Fe0.95Ti0.05 sample annealed at 1073 K had much better anti–corrosion properties than other alloys studied. This finding can be correlated with the extremely high concentration of titanium on the surface, which was more than four times that of iron. In contrast to other alloys studied in this work, the passive layer formed on the surface of Fe0.95Ti0.05 greatly enhanced its resistance to corrosion. [ABSTRACT FROM AUTHOR]

The article is a review of the latest European research on the problems of iron corrosion in seawater. Such damages are typical for objects of marine archaeology, in particular shipwrecks. For a long time, the study of such corrosion processes was complicated by the fact that samples taken in seawater quickly oxidized in the air and their composition changed significantly. In the early 1980s, after the development of sampling techniques, the study of underwater artifacts corrosion began to develop faster and more efficiently. First of all, the basic processes of iron corrosion and the factors that stimulate them are discussed in the article. These include sea­water salinity, oxygen concentration, microbiological activity, pH, temperature, and water circulation patterns, which, in turn, influence the prevalence of other parameters. Next, the iron corrosion products characteristic of the marine environment are described in detail. Finally, the role of microorganisms in the corrosion process and their influence on the preservation of the monument are highlighted.

An outstanding goal in planetary science is to understand how terrestrial cores evolved to have the compositions, thermal properties, and magnetic fields observed today. To achieve that aim requires the integration of datasets from space missions with laboratory experiments conducted at high pressures and temperatures. Over the past decade, technological advances have enhanced the capability to conduct in situ measurements of physical properties on samples that are analogs to planetary cores. These challenging experiments utilize large-volume presses that optimize control of pressure and temperature, and diamond-anvil cells to reach the highest pressures. In particular, the current experimental datasets of density, compressional velocity, viscosity, and thermal conductivity of iron alloys are most relevant to the core conditions of small terrestrial planets and moons. Here we review the physical properties of iron alloys measured in the laboratory at conditions relevant to the cores of Mars, the Moon, and Mercury. We discuss how these properties inform models of core composition, as well as thermal and magnetic evolution of their cores. Experimental geochemistry (in particular, metal-silicate partitioning experiments) provides additional insights into the nature and abundance of light elements within cores, as well as crystallization processes. Emphasis is placed on the Martian core to discuss the effect of chemistry on core evolution.

Three titanium alloys with 0.5, 6, and 9 wt.% iron were investigated, and the samples were pre-annealed in three different regions of the Ti-Fe phase diagram, namely β, α+β, and α+FeTi. After annealing, five samples of different phases and structural compositions were studied. They were then subjected to the high-pressure torsion (HPT). The microstructure of the samples before and after HPT treatment was studied using transmission and scanning electron microscopy. The microstructure of the samples obtained during heat treatment before HPT treatment had a fundamental effect on the microstructure after HPT. Grain boundary layers and chains of particles formed during the annealing process made it difficult to mix the material during HPT, which led to the formation of areas with non-uniform mixing of components. Thus, the grain boundary layers of the α-phase formed in the Ti-6wt % Fe alloy after annealing at 670 °C significantly decreased the mixing of the components during HPT. Despite the fact that the microstructure and phase composition of Ti-6wt % Fe alloys pre-annealed in three different regions of the Ti-Fe phase diagram had significant differences, after HPT treatment, the phase compositions of the studied samples were quite similar. Moreover, the measured micro- and nanohardness as well as the Young's modulus of Ti-6wt % Fe alloy had similar values. It was shown that the microhardness of the studied samples increased with the iron content. The values of nanohardness and Young's modulus correlated well with the fractions of β- and ω-phases in the studied alloys.

The current trends of production of casts are directed towards production of components disposing of higher accuracy, increased quality of surface and homogenous structure. In case of a thin-walled cast the development of speed of pressing and of pressure was observed inside the mould cavity during pressure die casting of ferrous alloys. In case of die casting of ferrous alloys the attention was paid to life service of a pressing piston and of a filling chamber. The optimal temperature of the steel casting ranges from 1600 to 1750°C and optimal mould temperature ranged from 220 to 260°C. The residues having occurred in gates reached the hardness of 38 HRC and in case of casts the value was of 45 HRC. Influence of acting of resistance pressure on the thin-walled casts only minimally. With the increasing resistance pressure the structure becomes more fine-grained and along with the increasing thickness of the wall the influence of the resistance pressure increases as well. Technology of pressure die casting of iron alloys can be compared with the pressure die casting technology of aluminium alloys. As standard, for pressure die casting the cast irons with carbon content of lower than 3% are recommended.

This review aims to comprehensively and systematically analyze the anodic oxidation process to form nanostructured oxide films on the surface of the most technologically relevant Fe-based alloys and steels. A special emphasis is put on detailed analysis of the mechanisms of the anodic formation of Fe-based nanostructured materials. The effect of anodizing parameters including the type of Fe-alloy, electrolyte composition, potential/current regimes, as well as various post-treatment procedures (including annealing treatment) on the growth, morphology, composition, and properties of the resulting oxide films is discussed in detail. Examples of possible applications of the anodic films grown on Fe-alloys in various fields including photocatalysis, energy storage, sensors, biomedicine, and others are also provided. Finally, current trends, challenges, and perspectives in the anodizing of Fe-alloys are addressed. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of High Pressure Physics is the property of Chinese Journal of High Pressure Physics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present work is aimed at examining the effect of solid solution on the development of recrystallization microstructure and texture in FCC materials where SFE remains unchanged on alloying addition. To elucidate the mechanisms of texture formation during recrystallization, pure Ni and Ni-Fe (20 and 40 wt.% Fe) alloys were investigated. After recrystallization, pure Ni showed a cube and a non-uniform α-fibre texture, whereas the Ni-Fe alloys showed a texture characterised by the rotated cube component, brass recrystallization (BR) orientation, and a non-uniform α-fibre. Addition of Fe to pure Ni has led to some fine differences in the recrystallization texture that have been attributed to the role of highly heterogeneous deformed microstructure in the Ni-Fe system because of alloying. However, in all the cases Cu-oriented grains are prone to early recrystallization due to relatively more heterogeneously deformed regions, whereas deformed grains having orientation <110> || ND have shown slow recrystallization. In all cases, the entire stage of recrystallization is dominated by the formation of annealing twin (Σ3) boundary. The mobility of these twin boundaries plays an important role in the evolution of the recrystallization texture, which in turn, depends on its coherency, i.e. grain boundary plane (K1) of twin boundaries. The mechanism of evolution of recrystallization texture and the role of different deformation features during recrystallization is investigated. The cellular automata simulation technique was used to simulate the recrystallization behaviour of the alloys. The simulation results were used to discuss experimental observations. [ABSTRACT FROM AUTHOR]