This study proposes a hybrid experimental-thermodynamic approach to determine the solubility products of rare earth oxysulfides and establish phase equilibria in molten copper. By combining limited experimental data at 1473 K with thermodynamic modeling, we derived temperature-dependent solubility product expressions (1340-1500 K) for Y2O3, YS, Y2O2S, Ce2O3, CeS, and Ce2O2S. Thermodynamic analysis conclusively rules out the formation of Y2S3 and Ce2S3. We systematically analyzed the formation criteria for RE2O2S, RES, and RE2O3 phases in liquid copper and constructed Y/Ce-O-S equilibrium diagrams at 1373 K and 1473 K. These results can provide essential foundational data for copper metallurgy for rare earth additions.

The adsorption of rare-earth Y-based inclusions (Y, Y2O3, Y2O2S) on Al2O3, YAlO3, and Y2O3 refractory surfaces is a primary cause of nozzle clogging during the continuous casting of rare-earth steels. Conventional anti-clogging strategies, being passive and offline, lack real-time adjustability. This study aims to elucidate the mechanism by which external positive charge modulates interfacial adsorption. Using first-principles calculations combined with partial density of states, charge density difference, and thermodynamic analyses, we investigated the adsorption behavior of Y, Y2O3, and Y2O2S on Al2O3 (001), YAlO3 (001), and Y2O3 (001) surfaces under neutral and positively charged states (+2, +4). A triple inhibition mechanism is revealed: electronically, external charge disrupts O-p and Y-d orbital hybridization, attenuating interfacial covalent bonding; electrostatically, the net positive charge shifts the interfacial interaction from attraction to repulsion, creating a physical barrier; and thermodynamically, the Gibbs free energy change ΔG increases under charged conditions, indicating a quantifiable reduction in adsorption spontaneity. These findings provide a theoretical basis for the development of active anti-clogging strategies in rare-earth steel production.

Hot deformation effectively refines the microstructure and homogenizes the composition of high-nitrogen martensitic stainless steel (HNMSS), but its influence on austenite stability during subsequent cooling remains unclear. In this study, the effect of the hot deformation strain on austenite stability in HNMSS 30Cr15Mo1N0.37 was investigated by means of a Gleeble thermomechanical simulator, X-ray diffraction (XRD), electron back-scatter diffraction (EBSD) and transmission electron microscopy (TEM). The austenite stability is evaluated by the austenite fraction measured via XRD at room temperature. The results show that the austenite content in HNMSS 30Cr15Mo1N0.37 gradually increases with the strain range from 0 to 0.8. The austenite fractions are 69.5%, 73.1%, and 80.7% when the strains are 0, 0.4, and 0.8, respectively. At a strain of 0.14, dislocation accumulation leads to the formation of dislocation cells and sub-grains within austenite, which enhances its stability. When the strain exceeds 0.36, the austenite grains are significantly refined, the austenite stability is attributed to the synergistic effects of dislocation accumulation and grain refinement, which collectively increase the resistance to martensitic transformation. Furthermore, both recrystallized grains and dislocation cells influence the morphology and size of martensite laths. The martensite laths are significantly refined from 100 nm at a strain of 0 to 35 nm as the strain reaches 0.8, and their morphology changes from straight to curved.

Bainite transformation has long been a major research focus in materials science, particularly the development of quantitative models for its transformation kinetics. In this study, the morphological evolution, kinetics, effects of prior austenite grain size (PAGS), and the influence of fast cooling rate on lower bainite (LB) transformation kinetics of a high-strength low-alloy steel were investigated. Laser scanning confocal microscopy, thermal simulation, and electron backscattered diffraction experiments were utilized. A specific kinetic equation for LB transformation was established. The results demonstrated that: (i) the kinetic constant was approximately proportional to the logarithmic volumetric PAGS and the square of cooling rate; (ii) the nucleation number per unit volume decreased with increasing PAGS; and (iii) the overall LB packet growth rate increased with both PAGS and cooling rate. The key factor in obtaining fine LB packets was to increase the nucleation number per unit volume of LB, which could be achieved through two approaches: reducing PAGS and modulating the cooling rate. However, reducing PAGS had a much stronger effect compared to modulating the cooling rate.

ZrCo alloys are widely recognized as ideal hydrogen isotope storage candidates for the International Thermonuclear Experimental Reactor (ITER). However, their practical application is severely hindered by hydrogen desorption effects and surface poisoning caused by impurity gases. This study developed Zr1-xYxCo (x = 0-0.15) alloys through rare earth element Y microalloying and systematically investigated the relationship between structure and properties. Results demonstrated that the optimal Y substitution (x = 0.05) significantly enhanced initial hydrogen absorption kinetics, reducing the saturation time from 50,189 s to 2,445 s-a reduction of approximately 95%. Additionally, the Zr0.95Y0.05Co alloy exhibited excellent antidesorption performance, maintaining its hydrogen storage capacity after 13 h at 500 degrees C. In terms of impurity resistance, the optimized alloy achieved an 85.3% capacity retention rate after 50 cycles in H-2 + 1000 ppm of O-2 atmosphere, significantly outperforming the original ZrCo alloy (23.4%). XPS analysis revealed a "self-sacrifice" mechanism, where Y preferentially forms a dense Y2O3 protective layer. This layer effectively inhibits oxygen diffusion while preserving the metallic state of the active Zr and Co sites. These findings suggest that Zr0.95Y0.05Co is a potential material for robust hydrogen isotope storage and transport systems.

The effects of yttrium (Y) addition on the formation of inclusions in 0.5C-1Cr-0.2Mo-0.1V spring steel were studied via thermodynamic calculations and scanning electron microscope (SEM) coupled with energy dispersive spectrum (EDS). According to thermodynamic calculations of Gibbs free energy, [Y] reacts with [O] and [S] but not with [C] in molten steel, with Y2O2S and Y2O3 being more easily formed inclusions in steel at 1873 K than YS and Y2S3 when the Y content is less than 0.06%. The experimental results show that the inclusions in spring steel without Y addition are mainly large irregular aluminum silicate, Al2O3-SiO2-TiO2 and MnS inclusions. The addition of 0.011% Y can eliminate large inclusions and form square Y2O3 and complex Y2O3-Y2O2S inclusions with Y2O2S in the core and surrounding Y2O3. When the Y content increased to 0.019%, the size of Y2O3 decreased, and isolated spherical Y2O2S formed. The addition of 0.031% Y can further decrease the size of Y2O2S, and Y2O3 is replaced by YS. A good consistency was observed between the calculated result of the Gibbs free energy and the experimental result. Moreover, a three-dimensional stability diagram of precipitation under equilibrium conditions at 1873 K is established to predict the formation sequence of Y-containing inclusions with different Y contents. The formation sequences are Y2O2S -> Y2O3 with Y contents in the range of 0.01-0.02%, YS -> Y2O2S -> Y2O3 with Y contents in the range of 0.02-0.06% and Y2S3 -> YS -> Y2O2S -> Y2O3 with Y contents in the range of 0.06-0.08%.

This work investigates acicular ferrite (AF) transformation through morphological evolution analysis, kinetic studies, and cooling rate effects using laser scanning confocal microscopy, thermal simulation, and electron backscattered diffraction experiments. The results demonstrate that AF transformation follows a continuous nucleation model and one-dimensional growth model, leading to the development of a new AF kinetic equation. The study quantitatively analyzes cooling rate effects (6.3–19.4 K/s) on the kinetic constant and qualitatively examines its impact on nucleation constant, nucleation number density, and overall AF growth rate. Key findings include: (i) kinetic constant shows quadratic dependence on cooling rate, (ii) nucleation constant and nucleation number density increase with cooling rate, and (iii) overall AF grain growth rate shows no pronounced dependence on cooling rate. These results confirm that higher cooling rates promote finer AF grain formation. Building on this kinetic understanding, the work predicts and verifies prior austenite grain size (PAGS) effect on AF transformation that decreasing PAGS is beneficial to obtain fine AF grains. The comprehensive findings significantly advance fundamental knowledge of AF transformation kinetics.

This study aims to reveal the intrinsic mechanism by which external positive charge inhibits the adsorption of rare earth Y-based inclusions (Y, Y₂O₃, Y₂O₂S) on MgO and Al₂O₃ refractory surfaces, thereby providing a theoretical foundation for the active control of nozzle clogging during the continuous casting of rare earth steels. To this end, first-principles calculations based on density functional theory were employed, integrated with partial density of states analysis, charge density difference visualization, and high-temperature thermodynamic evaluations. The adsorption behaviors under neutral and positively charged states (+ 2, + 4) were systematically compared. The results demonstrate that external positive charge suppresses interfacial adsorption through a triple mechanism. Electronically, it disrupts the energy alignment and orbital hybridization between O-p and Y-d states, leading to significant attenuation of interfacial covalent bonding. Electrostatically, the net positive background reverses the local interfacial environment from electrostatic affinity to repulsion, establishing a physical barrier that hinders adsorbate approach. Thermodynamically, the Gibbs free energy change ΔG increases markedly under charged conditions, reflecting a quantifiable and universal reduction in adsorption spontaneity across all adsorbates and substrates. These findings clarify the mechanism of external charge inhibiting the adsorption of rare earth inclusions in molten steel by refractory.

This study proposes a hybrid experimental-thermodynamic approach to determine the solubility products of rare earth oxysulfides and establish phase equilibria in molten copper. By combining limited experimental data at 1473 K with thermodynamic modeling, we derived temperature-dependent solubility product expressions (1340–1500 K) for Y 2 O 3 , YS, Y 2 O 2 S, Ce 2 O 3 , CeS, and Ce 2 O 2 S. Thermodynamic analysis conclusively rules out the formation of Y 2 S 3 and Ce 2 S 3 . We systematically analyzed the formation criteria for RE 2 O 2 S, RES, and RE 2 O 3 phases in liquid copper and constructed Y/Ce–O–S equilibrium diagrams at 1373 K and 1473 K. These results can provide essential foundational data for copper metallurgy for rare earth additions.

The 0.5C – 1Cr – 0.2Mo – 0.1V spring steel without and with 0.0061 wt% rare earth (RE)‐yttrium (Y) addition is prepared via vacuum induction melting, hot rolling, quenching and tempering, and the effects of Y addition on the microstructure evolution and mechanical properties of spring steel are investigated. The results show that Y addition can reduce the degree of microsegregation, refine the size of prior‐austenite grains during the austenitization process after hot rolling, and effectively remove and modify oxide inclusions during the solidification process. The martensite block tends to be equiaxed and refined, and the size of the martensite lath within the block also decreases with Y addition after quenching. The lamellar M 3 C carbide precipitates along the prior martensite lath boundary during tempering. Y addition can refine the lamellar M 3 C carbides and promote the formation of spherical M 7 C 3 carbides that are evenly distributed in laths. On the basis of the microstructure analysis mentioned above, the microstructure of 0.5C – 1Cr – 0.2Mo – 0.1V spring steel can be improved by the addition of Y, resulting in a significant increase in the strength, yield ratio and ductility of the steel.

Q355 steel represents one of the highest-volume production low-alloy steels globally. The high-Ti low-Mn alloy design significantly enhances its cost-effectiveness. This study investigates the microstructure and mechanical properties of a developed high-Ti low-Mn Q355 steel across two thickness specifications, with comparative analysis against conventional Q355B steel. Through elucidation of the strengthening and toughening contributions, the critical production requirement is identified: promoting TiC particle precipitation during rolling. This finding provides fundamental guidance for optimizing production processes and refining chemical compositions. Results demonstrate that under current processing conditions, 25 mm-thick high-Ti low-Mn Q355 steel plate achieves all design objectives, satisfying Grade B and even Grade C requirements. The enhanced strength and superior impact toughness (at both 20 and 0 degrees C) primarily derive from grain refinement and TiC precipitation.

Thermodynamic models are employed to describe the equilibrium between nonstoichiometric carbonitride and the Fe-based solid solution. The solubility of fcc Ti and fcc V in the Fe-based solid solution was developed separately. Values for four thermodynamic interaction parameters of the nonstoichiometric carbonitride were determined using equilibrium equations, by comparing the calculated results with previously published experimental data. Specific solubility product expressions for TiC_xN_y and VC_xN_y in austenite (containing Mn, Ni, Cr, and Mo as solid solution elements) and ferrite (containing Mn and Ni as solid solution elements) were then developed. The calculated results in this study show good agreement with both calculated results from ThermoCalc and experimental data from earlier references, demonstrating their reliability. The developed solubility products of TiC_xN_y and VC_xN_y are as follows (solubility products of TiC , TiN , VC , and VN can be referenced from our previous work). log^α /K_TiC_ xN_y=xlog^α /K_TiC+ylog^α /K_TiN+(1-x-y)log^α /K_Ti+xlogx+ylogy+(1-x-y)log(1-x-y)+xy121/T-x(1-x-y)4709/T-y(1-x-y)2093/T, log^α /K_VC_ xN_y=xlog^α /K_VC+ylog^α /K_VN+(1-x-y)log^α /K_V+xlogx+ylogy+(1-x-y)log(1-x-y)+xy13/T-x(1-x-y)3663/T-y(1-x-y)2093/T .

The morphology and types of inclusion, as well as the microstructure, fundamentally affect the properties of high-strength peritectic steel. Rare earth elements not only modify inclusions but also act on the transformation of the microstructure. In this paper, the evolution mechanism of yttrium for the inclusions and microstructure in high-strength peritectic steel was investigated through experimental testing and thermodynamic analysis. The results show that yttrium treatment can modify the main large-sized irregular inclusions into spherical or near-spherical rare earth inclusions, accompanied by a reduction in the number density, area fraction, average diameter, and aspect ratio of inclusions. The evolution route for the inclusions follows Al2O3 + MnS + Al2O3-MnS→Y2O3 + Y-O-S + Y-S + Y-O-S-MnS with yttrium addition. The microstructural characteristics of yttrium-free steel show significant differences from those of yttrium-containing steel. Compared to yttrium-free steel, the yttrium-0.015 wt.% steel shows a refined austenite structure with more uniform size distribution and the absence of grain boundary ferrite films. The Y2O3 and Y2O2S inclusions mainly formed in liquid steel were found along the austenite grain boundary to prevent the grain growth and the formation of ferrite films. Additionally, after adding rare earth yttrium, the fraction of high-angle grain boundaries (HAGBs) increases, together with a decrease in the fraction of low-angle grain boundaries (LAGBs) in steel. The research results can provide a theoretical basis for the application of adding rare earth yttrium to high-strength peritectic steel.

The initial configurations of nano-lanthanum oxide clusters (La2O3)n (n = 1-7) were constructed using a combination of the artificial bee colony algorithm and density functional theory. For the first time, the medium-sized cluster structure with seven lanthanum oxide molecules was established. By optimizing different structures and calculating the vibration frequency, many new configurations different from previous studies were obtained. The average binding energy, second-order difference energy, HOMO-LUMO energy gap, density of states, and molecular orbital properties of the cluster system were analyzed. On this basis, the thermodynamic properties and behavior of nano-lanthanum oxide clusters under different temperature and molecular number conditions were discussed. The results show that with an increase in the number of molecules, the cluster structure gradually changes from cage-like to spatial ladder-like, and finally to ellipsoid-like. The nanoclusters are stable overall, with relatively higher stability when n = 2,4, and the effect of the lanthanum oxygen atomic orbital on the molecular orbital of the cluster is analyzed. The Cv, Cp, S, and H of (La2O3)n (n = 1-7) clusters increase with temperature, and increase with the number of molecules, while G and Gv decrease with temperature, with changes in the number of molecules greatly affected by E (0 K) and T. The thermodynamic properties of lanthanum oxide clusters with larger molecular numbers are more sensitive to temperature changes. The results provide a theoretical basis for the evolution mechanism of lanthanum oxide clusters-crystals and valuable information for further study of the growth law of rare earth oxide molecular clusters.

A thermodynamic method based on the ionic two-sublattice liquid model was developed to deduce the relationships between the solubility products of different rare earth compounds. Solubility products of ${\rm Y}_2{\rm O}_3$Y2O3, ${\rm Y}_2{\rm O}_2{\rm S}$Y2O2S, ${\rm YS}$YS, ${\rm C}{\rm e}_2{\rm O}_3$Ce2O3, ${\rm C}{\rm e}_2{\rm O}_2{\rm S}$Ce2O2S, and ${\rm CeS}$CeS in liquid nickel were obtained from experimental data in the temperature range of 1728 to1890 K, respectively. Subsequently, solubility products of ${\rm Y}_2{\rm S}_3$Y2S3, ${\rm C}{\rm e}_2{\rm S}_3$Ce2S3, and ${\rm C}{\rm e}_3{\rm S}_4$Ce3S4 were calculated. Using these results, the ${\rm Y}-{\rm O}-{\rm S}$Y-O-S and ${\rm Ce}-{\rm O}-{\rm S}$Ce-O-S equilibria were studied. The equilibrium phases within ranges of oxygen and sulphur concentrations, when the addition of rare earth (RE) element was within several hundred ppm, were plotted at 1773, 1823, and 1873 K, respectively. The obtained results were consistent with the experimental data. The present thermodynamic method can be used to determine the solubility products of rare earth compounds and ${\rm RE}-{\rm O}-{\rm S}$RE-O-S equilibria in other molten metals. On a d & eacute;velopp & eacute; une m & eacute;thode thermodynamique bas & eacute;e sur le mod & egrave;le liquide ionique & agrave; deux sous-r & eacute;seaux pour d & eacute;duire les relations entre les produits de solubilit & eacute; de diff & eacute;rents compos & eacute;s de terres rares. On a obtenu les produits de solubilit & eacute; de Y2O3, Y2O2S, YS, Ce2O3, Ce2O2S et CeS dans le nickel liquide & agrave; partir de donn & eacute;es exp & eacute;rimentales dans la plage de temp & eacute;ratures de 1728 & agrave; 1890 K, respectivement. Ensuite, on a calcul & eacute; les produits de solubilit & eacute; de Y2S3, Ce2S3 et Ce3S4. En utilisant ces r & eacute;sultats, on a & eacute;tudi & eacute; les & eacute;quilibres de Y-O-S et de Ce-O-S. On a trac & eacute; & agrave; 1773, 1823 et 1873 K, respectivement, les phases d'& eacute;quilibre dans les plages de concentrations d'oxyg & egrave;ne et de soufre, lorsque l'ajout d'& eacute;l & eacute;ment de terre rare (TR) & eacute;tait de l'ordre de quelques centaines de ppm. Les r & eacute;sultats obtenus & eacute;taient coh & eacute;rents avec les donn & eacute;es exp & eacute;rimentales. On peut utiliser la m & eacute;thode thermodynamique pr & eacute;sente pour d & eacute;terminer les produits de solubilit & eacute; des compos & eacute;s de terres rares et les & eacute;quilibres TR-O-S dans d'autres m & eacute;taux fondus.

Thermodynamic models were established based on the ionic two-sublattice liquid model to deduce a concentration relationship of rare earth, sulphur, and oxygen and to calculate the solubility product of rare earth oxysulphide in liquid iron at 1811-1973 K. Three interaction parameters were determined for the systems containing oxygen and/or sulphur. First, the expressions for solubility products of Y, Ce, and Nd oxides and sulphides were deduced, respectively. Subsequently, the expressions for solubility products of Y, Ce, and Nd oxysulphides were developed using approximation of Gibbs energy calculations, respectively. The obtained results were in good agreement with the experimental data. The expressions developed for solubility products are log liqK(Y2O2S)(0) approximate to 19.1 - 60768/T, log liqKCe(2O2S)(0) approximate to -4.2 - 16284/T, and log liqK(Nd2O2S)(0) approximate to 23.2 - 66889/T. The proposed thermodynamic model can be used to obtain solubility products of other oxysulphides in liquid metals by substituting the corresponding element with the rare earth.

The traditional blast furnace ironmaking process is the most widely used ironmaking process globally, yet it is associated with significant drawbacks, including high energy consumption and carbon emissions. To achieve low-carbon ironmaking, researchers have developed hydrogen ironmaking, which is capable of achieving lower CO2 emissions. Nevertheless, the distribution behavior of impurities has been less studied in the existing research on hydrogen ironmaking. Therefore, in this study, the factors affecting the slag properties and distribution of impurity elements during hydrogen ironmaking were investigated using FactSage, and smelting experiments were carried out. The results show that temperature has the greatest influence on the distribution behavior of the impurities, and excessively elevated temperatures result in the ingress of a significant quantity of impurities into the reduced iron. Reduced iron with a purity of 98.52% was obtained under the conditions of 10%, 10%, 2%, and 2% ratios of CaO, SiO2, MgO, and Al2O3, respectively, a hydrogen flow rate of 12 mL/min, and a temperature of 1400 °C; Lg L Mg, Lg L Al, Lg L Si, and Lg L Ca were 2.72, 2.41, 3.36, and 2.45, respectively (“L” stands for slag-to-metal ratio). The slag was mainly dominated by the silicate, and the iron was mainly lost in the form of mechanical inclusions in the slag. This study will enrich the basic theory of hydrogen ironmaking and is of great significance for the realization of carbon neutralization.

Argon bubble blowing enhanced vacuum refining is a crucial process to remove hydrogen element in molten steel for high-quality steel manufacturing. However, the whole refining process is a black-box operation and the field information inside the reactor is not clear yet. In this work, an integrated mathematical model that coupling computational fluid dynamics and degassing chemical reaction is established to investigate dehydrogenation behavior under vacuum condition. The model accounts for three potential reaction sites to clarify the dehydrogenation mechanism of molten steel in detail. The simulation results indicate that the hydrogen removal by argon bubble surface contributes the most, followed by steel free surface, and little by bulk steel near the bath surface where the dehydrogenation occurs mainly at the initial treating stage. The total hydrogen removal ratio increases with reducing vacuum pressure and increasing the argon gas flow rate, but is independent of the initial hydrogen content.