Hot compression tests were performed on a solution-treated Mg-9Gd-1.5Zn-0.8Sn (wt.%) alloy at 370–490 °C and 0.002–1 s-1, and its microstructural evolution was systematically investigated using multiscale characterization. The results show that increasing deformation temperature and decreasing strain rate significantly promote dynamic recrystallization (DRX) and improve microstructural homogeneity. With increasing DRX fraction, the overall basal texture is progressively weakened, mainly owing to the increased fraction of orientation-dispersed DRXed grains and the gradual consumption of strongly textured deformed grains. Slip-system distribution and in-grain misorientation axis (IGMA) analysis indicate that non-basal slip is widely activated during hot compression. In particular, pyramidal II slip is more readily activated under high-temperature and low-strain-rate conditions, thereby enhancing strain accommodation involving the c-axis component and promoting intragranular lattice rotation, whereas a higher strain rate suppresses DRX and consequently reduces texture weakening. Further analysis reveals that different DRX mechanisms exert distinct effects on grain orientation evolution: grains formed by discontinuous DRX (DDRX) retain a strong orientation correlation with adjacent parent grains, whereas grains associated with twinning-induced DRX (TDRX) exhibit a higher degree of orientation dispersion. In addition, a flow-line fine-grained band extending along the deformation direction is observed in local regions. Its formation is closely related to second-phase-induced local strain incompatibility, where TDRX provides favorable interfacial nucleation conditions through double tensile twins, while continuous DRX (CDRX) promotes the sustained development of the fine-grained band through continuous intragranular rotation and progressive subgrain misorientation. The synergistic effect of TDRX and CDRX therefore contributes to local texture weakening.

Hot deformation behavior, constitutive equation, dynamic materials model (DMM), microscopic dislocation slip, and dynamic recrystallization (DRX) mechanisms of Mg-9Gd-1.5Zn-0.8Al (wt%) alloy were analyzed jointly using a Gleeble-1500 thermomechanical simulator. The strain-compensated constitutive model (Q = 354.058 kJmol(-)(1)) was established and combined with the DMM to construct processing maps, which clearly defined a safe processing window centered at 460-500 degrees C and 0.003-0.01 s(-)(1). Microstructural mechanism investigation revealed, via IGMA analysis, a systematic clarification of the dynamic transition in dominant dislocation slip modes under different thermomechanical parameters: prismatic slip dominated at low temperatures and low strain rates, whereas synergistic activation of basal slip and pyramidal slip occurred at high temperatures. Furthermore, the study revealed competitive and cooperative relationships between DDRX and CDRX, while limited twin-induced dynamic recrystallization (TDRX) also contributed uniquely to texture weakening. This research provides a theoretical basis and experimental evidence for controlling micro-deformation mechanisms and optimizing the microstructure of high-rare-earth magnesium alloys through hot working processes.

Hot compression tests were performed on a solution-treated Mg-4Sm-3Gd-1Al-0.5Zn (wt%) alloy using a Gleeble-1500D thermomechanical simulator to systematically investigate its flow behavior, critical strain for dynamic recrystallization (DRX), safe processing window, and microstructural evolution. The results show that the flow stress decreases with increasing deformation temperature but increases with increasing strain rate, indicating a pronounced thermally activated deformation behavior. A sixth-order polynomial was employed to smooth the flow curves, based on which an Arrhenius-type constitutive equation was established. The average hot deformation activation energy was determined to be 334.88 kJ·mol−1. The critical strain for DRX initiation was identified from the strain hardening rate, and a linear empirical relationship between the critical strain and peak strain was established. Under all deformation conditions, the critical strain (εc) was lower than the peak strain (εp), following the relationship [[EQUATION]]. The processing map reveals that the safe processing window is mainly located in the low-strain-rate domain at 420-510°C. EBSD analysis shows that the microstructures within the representative processing window exhibit a bimodal feature consisting of fine recrystallized grains and coarse deformed grains, and that the DRX evolution is jointly governed by the competition between nucleation and grain growth. IGMA analysis indicates that hot deformation is dominated by -type lattice rotation, suggesting that basal slip and pyramidal II slip jointly accommodate the plastic deformation.

The T6-treated AZ80 magnesium alloy is composed of three phases: α-Mg, Mg17Al12, and Al18Mn19. This study reveals a synergistic corrosion inhibition effect in silane coupling agent-organic ligand systems. Specifically, the dodecyltrimethoxysilane (DTMS)-2-2’bipyridyl (bpy) system exhibits optimal corrosion inhibition performance, achieving an inhibition efficiency of 87.96% as determined by weight loss test. Electrochemical measurement results further indicate that bpy acts as an anodic inhibitor, while DTMS functions as a mixed-type inhibitor. The combined application of these two inhibitors further suppresses the anodic corrosion of AZ80 alloy. The synergistic mechanism between DTMS and bpy is attributed to the formation of a composite film. The protective mechanism of this film originates from two key processes: the formation of a hydrophobic monolayer through silane hydrolysis and cross-linking, and the continuous deposition reaction facilitated by the coordination of bpy with Mg2+. This dual mechanism collectively provides sustained and enhanced anodic protection, thereby significantly improving the corrosion resistance of the AZ80 alloy.

This paper studies the dynamic recrystallization (DRX) behavior and hot workability of Mg-9Gd-1.5Zn-0.8Sn alloys via hot compression tests. Conducted on a Gleeble-1500D thermal simulator, the tests cover deformation temperatures of 370–490 °C and strain rates of 0.002–1 s-1. The research establishes a DRX critical strain model (based on the inflection of the work hardening rate curve), a DRX kinetic model (using the Avrami equation), and processing maps (derived from the dynamic material model). By integrating these maps with microstructural evolution observations, it identifies instability mechanisms and optimal hot-working regions. Results show that critical strain (εc) declines with higher temperatures or lower strain rates—conditions that facilitate DRX. Thus, the recommended effective hot-working range is 400–470 °C for temperature and 0.002–0.05 s-1 for strain rate. This paper systematically investigates the dynamic recrystallization behavior (DRX) and hot workability of Mg-9Gd-1.5Zn-0.8Sn alloys using a hot compression experimental system. The experiment was conducted using a Gleeble-1500D thermal simulator, which can generate deformation temperatures ranging from 370 to 490 °C and strain rates ranging from 0.002 to 1 s-1. The results indicate that the stress–strain curves exhibit a single-peak DRX behavior. The DRX critical strain model of the alloy is constructed according to the inflection characteristics of the work hardening rate curve. The DRX kinetic model is constructed in accord with the Avrami equation. The processing maps are derived from the dynamic material model. The instability mechanisms of these regions are investigated by combining the processing map and the microstructural evolution, and the most suitable regions for hot working are identified. It has been demonstrated that the critical strain εc of the alloy is reduced at higher deformation temperatures or lower strain rates, and that the DRX occurs more easily under these conditions. Therefore, the material is more suitable for hot working. The range of temperatures and strain rates that have been identified to be conducive to the effective hot working of the Mg-9Gd-1.5Zn-0.8Sn alloy include temperatures ranging from 400 to 470 °C and strain rates ranging from 0.002 to 0.05 s-1.

The present work systematically optimized the heat treatment technology of Mg–9Gd–1.5Zn–0.8Al (wt.

In this work, a cerium-containing composite conversion film has been prepared on the PbSb alloy to improve its corrosion resistance. Batch studies have been carried out to address the influence of various process parameters. Systematic investigations were conducted to elucidate the film formation mechanism and evaluate the corrosion resistance property. The morphology and chemical composition were characterized with scanning electron microscopy, fourier transform infrared and x-ray diffractometry. The corrosion resistance of the samples has been measured by electrochemical and immersion tests. The results show that with the increase in the concentrations of H2SO4, (NH4)4Ce(SO4)4 and polyvinylpyrrolidone PVPk30, as well as the treatment temperature, the corrosion resistance of the film first increases and then decreases slightly. The film quality is greatly influenced by the processing time. Cracks begin to appear in the film after 12 h. Both PVPk30 and cerium ions act as synergistic surface modifiers; as a result, the film formed under the relative optimum process is very compact and completely covered the substrate. The film, mainly composed of PbSO4 with trace amounts of oxides, cerium compounds and organic materials, exhibits significantly superior corrosion resistance compared to the bare alloy in a carbonic acid solution.

To investigate the effect of microstructure on the corrosion resistance of rail steel, different sizes of pearlite clusters and austenite grains were obtained via heat treatment of U75V rail samples at different temperatures. The effects of different pearlite cluster sizes and austenite grain sizes on the corrosion behavior and electrochemical properties of the rail samples were subsequently investigated via salt spray corrosion tests and electrochemical performance tests. The results show that the corrosion products of all the samples are composed of γ-FeOOH, α-FeOOH, and Fe3O4, and the microscopic morphology mainly manifests as clusters, needles, and flowers, indicating that the differences in microstructure do not affect the composition and morphology of the corrosion products. During the salt spray corrosion process, the average corrosion rate of all the samples decreased; however, with increasing corrosion time, there was still an overall increasing trend, and compared with that of the pearlite cluster samples, the average corrosion rate of the austenite samples exhibited relatively better corrosion resistance. In addition, for the same microstructure, samples with higher heat treatment temperatures that have larger austenite grains or smaller pearlite clusters exhibit higher average corrosion rates and self-corrosion current densities (Jcorr), lower charge transfer resistances (Rct), and poorer corrosion resistance owing to the decrease in the relative area of the grain boundaries of the austenite grains and the increase in the lamellar spacing within the pearlite clusters. A smaller grain boundary area and larger lamellar spacing result in a much greater probability of corrosion occurring, thereby increasing the susceptibility of the sample to corrosion in a salt spray environment.

Pb-Sb alloy is an excellent cutting rope material, however, easy to be corroded in CO2-containing environment. Hereby, the Pb-Sb alloy was heat-treated, and its microstructure and corrosion behavior in H2CO3 solution were investigated. The morphology and chemical composition were characterized with scanning electron microscopy equipped with energy-dispersive x-ray spectroscopy, and x-ray diffractometry. The corrosion resistance of the samples has been measured by electrochemical and immersion tests. The hardness of the samples was also measured. The results showed that Sb was basically integrated into the Pb matrix after solution treatment at 290 °C for 1 h, and the grain size increased an order of magnitude. After aging treatment at 100 °C for 2 h, the hardness and corrosion resistance of the Pb alloy reached the highest, and the grain size of the alloy was larger than that of the original state, but was finer and more uniform than that of the samples after solution treatment and aging treatment for longer time due to the recrystallization. The decrease in the amount of large secondary phases and grain boundaries resulted in the improvement of the compactness of the corrosion products layer formed on the alloy surface during the corrosion test. In contrast, the excess of dispersed and fine secondary phases and coarser grains led to less protective corrosion products film and lowered the corrosion resistance after the solid-solution or longer-time aging treatment.

In this paper, the effect of Zn on the dynamic precipitation phase and DRX grain size of Mg-8Gd-4Sm-0.5Zr alloy was investigated by using OM, SEM, and TEM. The effect of Zn on the hot workability was investigated by constructing the DMM model. The variation of DRX behavior and microstructure evolution of the two alloys were investigated by constructing the CA-FE coupled model. The test was conducted using the Gleeble-1500 testing machine at deformation temperatures of 350-470 degrees C and strain rates of 0.002-1 s-1. The results show that the addition of Zn promotes the type and number of dynamically precipitated phases and refines the DRX grain size. The critical strain epsilon cdecreases with the addition of Zn, and the dynamic recrystallization level of 1Zn alloy is higher. The addition of Zn reduces the instability region and increases the workability region. The plastic deformability is optimized in the high-temperature P1 region. The nucleation site of DRX grains simulated by CAFE coupling is closely related to the dislocation density distribution. The DRX grains nucleate at grain boundaries and gradually expand into the surrounding grains. The standard deviation (S.D.) and the distribution of different sizes of DRX grains gradually increase with increasing temperature. Meanwhile, the relative errors between the simulated and experimental values for predicting the DRX grain sizes of the two alloys are mostly less than 10 %. It is verified that the coupled CA-FE simulation can accurately predict the variation of dynamic recrystallization behavior and microstructure evolution of materials under different deformation conditions.

PINE, integrated in the nuclear design software package PCM, is a lattice code developed by China Nuclear Power Technology Research Institute Co., Ltd. To calculate neutron kinetics parameters in high accuracy, the spatial distribution of adjoint flux is needed. In this work, the module for the resolution of 2D spatial distribution of adjoint flux is developed in PINE, which is based on the Method of Characteristics (MOC) solver. The corresponding Coarse Mesh Finite Difference (CMFD) method for acceleration and B1 correction in consideration of leakage effects are also presented in detail. Difference of homogenization techniques between the CMFD for forward and that for adjoint flux is focused. A primary analysis for the verification of this new-developed module is carried out, and it justifies the correctness of CMFD acceleration for adjoint flux in this work. Based on the neutron kinetics parameters experiments performed on IPEN/MB-01 facility, the new module for adjoint transport resolution as well as the corresponding B1 correction developed in PINE are validated. This work also justifies that neutron kinetics parameters are insensitive to rod insertion and multi-group effects of kinetics database.

In this paper, the corrosion resistance and mechanisms of rail specimens with different lamella spacings in a salt spray environment were evaluated and investigated. This investigation was achieved by controlling different cooling rates of pearlitic bodies through heat treatment to obtain various lamella spacings. The results indicated that the corrosion resistance of all the specimens decreased during the salt spray test. The specimens with slow cooling rates (resulting in large pearlitic sheet layer spacings) had poorer corrosion resistance than those with fast cooling rates. Specimens obtained with both fast and slow cooling rates (air cooling at a 0.01 degrees C/s cooling rate) displayed similar corrosion patterns. However, the corrosion stability of the specimen obtained at a cooling rate of 0.03 degrees C/s fluctuated considerably after 144 h of salt spray corrosion. This fluctuation was attributed to the transformations of corrosion products within the rust layer. The structural stability of the rust layer was related to the defects present in the material. Large defects increase the instability of the rust layer, thereby increasing the susceptibility to corrosion in a salt spray environment.

The creep behaviors of Mg-9Gd-2Nd-1Ca-0.5Zr alloy under the temperature 200-250 °C and the applied stress 50-90 MPa for 100 h were studied in a typical creep testing machine. The stress exponent n at different stresses and the creep activation energy Q at different temperatures were discussed. The results show that the aging state Mg-9Gd-2Nd-1Ca-0.5Zr alloy has excellent creep resistance at 200 °C/50 MPa, the steady state creep rate is only 2.675 × 10−9 s−1, and the stress exponent n and creep activation energy Q are 1.1 and 37 kJ/mol, respectively. As the creep temperature and creep stress increase, the creep strain and steady state creep rate increase gradually. The creep mechanism of the alloy is converted from grain boundary slip at 200 °C/50 MPa to dislocation climb at 225 °C/70 MPa. The power law creep fails at 250 °C/90 MPa. The creep mechanism is mainly influenced by the second phase and becomes more complex. The precipitated phases in the grain interiors are the coarse β1 phase and β phase after creep. The mechanism of creep fracture of the alloy is converted from brittle transgranular fracture at 250 °C/90 MPa to ductile fracture at 250 °C/70 MPa.

The dynamic recrystallization (DRX) behavior and hot workability of Mg-8Gd-4Sm-1Zn-0.5Zr alloys are investigated by the Gleeble-1500 test machine. The tests are performed at 350-470 degrees C with a strain rate of 0.002-1 s-1. The results show that the stress-strain curves exhibit a typical single-peak DRX behavior. The DRX critical strain model of the alloy is constructed according to the inflection characteristics of the work hardening rate curve. The DRX kinetic model is constructed according to Avrami equation. The 3D processing maps are obtained based on the dynamic material model. The mechanisms of instability regions are investigated by combining the processing map and the microstructural evolution, and the most suitable regions for hot working are identified. The critical strain epsilon c of the alloy is reduced at higher deformation temperatures or lower strain rates, and the DRX more easily occurs. That is, the material is more suitable for hot working. The optimum domain for hot working of Mg-8Gd-4Sm-1Zn-0.5Zr alloy is the temperature range of 400-470 degrees C and strain rate range of 0.002-0.05 s-1. The dynamic recrystallization (DRX) behavior and hot workability of Mg-8Gd-4Sm-1Zn-0.5Zr alloy are investigated by hot compression experiments. The critical strain model, DRX kinetic model and the processing maps are constructed by the stress-strain curves. According to the processing maps and evolution of the microstructure of the alloy at different strain conditions, the mechanisms of instability regions are studied, and the most suitable regions for hot working are identified.image (c) 2024 WILEY-VCH GmbH

In this paper, the dynamic recrystallization behavior and microstructure evolution during thermal deformation were simulated by coupling finite element (FE) and cellular automaton (CA) models. The thermal deformation tests were conducted on Mg-8Gd-4Sm-1Zn-0.5Zr alloy at deformation temperatures of 350–470 °C and strain rates of 0.002–1 s−1. The true stress-strain curves were obtained under different deformation conditions, and the microstructure evolution of the alloy was investigated. On this basis, the dynamic recrystallization kinetic model, grain size model, and Laasraoui-Jonas model for CA simulation were established. Meanwhile, the dynamic recrystallization behavior of the alloy under different deformation conditions was simulated by inputting the relevant parameters of the model into the finite element CA simulation software. The simulation results show that the different strains, deformation positions, deformation temperatures, and strain rates have a significant effect on the dynamic recrystallization volume fraction and grain size of the alloy. The predicted DRX volume fraction and grain size are in good agreement with the experimental data, with errors mostly below 10

采用光学显微镜、扫描电镜、X射线衍射仪、透射电镜、电子拉伸实验机等研究了铸态Mg-10Y-xZn-0.5Zr(x=1,1.5,2(％,质量分数))合金的微观组织和力学性能.结果表明:铸态Mg-Y-Zn-Zr合金组织主要由α-Mg,LPSO相和W相组成,其中LPSO相的化学式为Mg12YZn,W相的化学式为Mg3Zn3Y2.LPSO相主要呈块状或层片状,随着Zn含量的增加,块状LPSO相体积分数逐渐增多,同时合金的屈服强度逐渐增加.当Zn含量为2％时,LPSO相形貌表现出以块状相为主.铸态Mg-10Y-2Zn-0.5Zr合金具有最佳的综合力学性能,其屈服强度、抗拉强度和延伸率分别为123.9,206.2 Mpa和12.06％.块状LPSO相体积分数的增加是合金力学性能提高的主要原因.

The corrosion resistance of as-cast Mg-xHo-3Sm-0.5Zr, solid solution and aged Mg-8Ho-3Sm-0.5Zr alloys was studied by electrochemical experiments, weight loss tests and microstructure analysis. The results showed that adding a proper amount of Ho to the as-cast alloy can refine the grain size. Furthermore, Ho can promote the precipitation of the Mg41Sm5 phase and form a new Mg24Ho5 phase. The Mg-8Ho-3Sm-0.5Zr alloy has the strongest corrosion resistance because of its uniform structure and the smallest grain size. Then, the Mg-8Ho-3Sm-0.5Zr alloy was heat treated. The results indicate that after solution treatment, the microstructure of the alloy is uniformly dispersed, and the second phase is dissolved in α-Mg, which improves the self-corrosion potential of the matrix. Its corrosion resistance is slightly better than that of the as-cast alloys. After aging treatment, a large number of second phases are uniformly dispersed to form a corrosion barrier, which further reduces the corrosion rate.