This study employed a gradient heat treatment strategy to efficiently acquire microstructure parameters and establish the microstructure-hardness relationship in Ti-6Al-4V-1.5Zr-1.0Nb-0.5Mo alloy, addressing the knowledge gap in rapid optimization of heat treatment windows. Gradient solution treatment in the α + β region (859-928 °C) revealed that hardness reaches a minimum at a Vαp/Vβt ratio of approximately 0.5, a condition to be avoided if aging is not applied. Subsequent aging at 500 °C, a common temperature for such alloys, highlighted the solution-treated sample at 908 °C as possessing high hardening potential, attributed to its high βt fraction (Vβt = 70%) and sufficient retained β phase that promoted fine αs precipitation. Gradient aging (502-590 °C) of this optimized microstructure further showed that peak hardness (>350 HV1, measured under a 1 kg load) was achieved at 502 °C and 551 °C, where the Vαp/Vβt ratio remained near the optimal 3:7, and the precipitated refined αs exhibited minimal width. The hardness of the bimodal microstructure is governed by two principal factors: the Vαp/Vβt ratio (optimum near 3:7) and the precipitation efficiency of refined αs from retained β phase. The gradient approach proves to be an effective high-throughput method for rapidly correlating heat treatment parameters with microstructure and properties, accelerating the design of heat treatments for titanium alloys.

Friction during high-temperature deformation strongly affects the flow behavior and microstructural uniformity of the TC4 alloy. In this study, hot compression tests were performed at 830–1080°C and strain rates of 0.01–10 s−1 under two lubrication conditions, tantalum foil (Ta) and tantalum foil + graphite sheet (Ta + C), to investigate the effects of lubrication on friction behavior, constitutive response, and microstructure. The results show that the friction factors under Ta + C lubrication are consistently lower than those under Ta lubrication, being about 0.17–0.63 and decrease with increasing temperature for both lubricants. The flow stresses are lower than the measured values, and the deviation increases with strain. At 830–880°C, the flow stress under Ta lubrication is significantly higher than that under Ta + C lubrication, and the flow curves exhibit more pronounced DRX characteristics. At 930–1080°C, the difference in flow stress between the two lubrication conditions becomes much smaller, and the flow curves tend to stabilize after the peak, suggesting DRV-dominated softening. Peak stress-based and strain-compensated Arrhenius constitutive equations were established for the α + β and β phase regions under both lubrication conditions, and both models showed high predictive accuracy. The activation energy values calculated under Ta + C lubrication are consistently lower than those under Ta lubrication, indicating that the reduced friction effect allows the constitutive parameters to better reflect the intrinsic hot-deformation response of alloy. Finite-element simulations at 880°C and 1 s−1 show that increasing the friction intensifies strain heterogeneity, with the equivalent strain in the specimen core being significantly higher than that near the die–specimen interface. EBSD analysis further reveals that Ta + C lubrication produces a finer and more homogeneous microstructure, whereas Ta lubrication is more likely to promote local recrystallization due to stronger friction-induced strain heterogeneity.

Pilger rolling and inter-pass annealing are key steps in the entire manufacture of FeCrAl alloy cladding tubes for light water nuclear reactors. It is particularly necessary to comprehensively understand the evolution and mechanisms of grain size, grain boundaries and texture of FeCrAl alloy tubes during Pilger rolling and annealing processes. In this paper, the average grain size of the FeCrAl alloy finished tube processed by multiple passes of small deformation Pilger cold rolling and inter-pass annealing is 9.8 mu m, and its microstructure is uniform. The FeCrAl alloy tube forms weaker textures mainly consisting of {112}<110>, {111}<110> and {111}<121> textures. There are significant differences in the strength of deformation texture among different rolling passes, and annealed texture tends to maintain the texture type of deformation texture corresponding to the pass and slightly enhance the strength. This small, uniform grain structure with weak texture is beneficial for the processing and service of cladding tubes. The results of this paper provide effective reference for the study of FeCrAl alloy cladding tubes.

In this work, kink bands (KBs) were introduced in Fe-Cr-Al alloys to simultaneously overcome strengthductility trade-off and enhance creep resistance. KBs-containing samples exhibit exceptional mechanical synergy at room temperature, achieving a yield strength of 950 MPa, an ultimate tensile strength of 1.06 GPa, a uniform elongation of 9.5 %, and a total elongation of 11.6 %. Results indicate that this enhancement originates from complementary strengthening mechanisms of KBs-induced hetero-grain refinement and hetero-deformation-induced (HDI) hardening. Moreover, KBs-mediated crack deflection and grain boundary delamination effects preserve ductility. At elevated temperature (400 degrees C), KBs maintain functional efficacy through persistent Hall-Petch strengthening and sustained HDI hardening despite significant grain boundary weakening. The suppression of boundary delamination arises fundamentally from reduced strain hardening differentials between grain clusters with high-density KBs and low-density KBs, mitigating intergranular crack initiation and propagation from interfacial strain incompatibility. Remarkably, KB-containing alloys exhibit superior creep resistance at 400 degrees C and 500 MPa compared to their homogeneous counterparts. Creep deformation is primarily governed by screw dislocation glide, which results in a very low creep rate (4.3651 x 10-9 s-1 ) and negligible creep strain, outperforming other cladding materials. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Heterogeneous structure exhibits superiority in improving mechanical properties, whereas their effects on fatigue damage properties have rarely been studied. In this work, we employed a high-throughput gradient heat treatment method (757-857 degrees C) to rapidly acquire the solution microstructure of the Ti-6554 alloy with different recrystallization degrees (0%, 40% and 100%), followed by the same aging treatment. The results showed that the beta-hetero structure exhibited a yield strength (sigma YS) of 1403 MPa, an increase of 6.7%, and a remarkable improvement in uniform elongation (UE) of 109.7%, reaching 6.5%, compared to the homogeneous structure. Interestingly, introducing a heterogeneous structure not only overcame the traditional trade-off between strength and ductility but also enhanced fatigue crack propagation (FCP) performance. During FCP process, beta-hetero structure, through hetero-deformation induced (HDI) strengthening effects, promoted the accumulation of geometric necessary dislocations (GNDs) within coarse alpha(S) phase, enabling faster attainment of the critical shear stress of twinning and increasing twinning density. This facilitated stress relief, improved plastic deformation in the crack tip zone, and increased the critical fast fracture threshold from 30.4 to 36.0 MPam(1/2) showing an enlarged steady state propagation region. This study provides valuable insights on tailoring fatigue damage tolerance through heterogeneous structure for titanium alloys.

In this work, an anomalous compression behavior at 300 °C was found in a Fe–Cr–Al alloy, where the stress value decreased with increasing the strain rate, presenting a counterintuitive strain rate sensitivity effect. The results indicate that variations in kinking activation are the primary contributors to this phenomenon. Kinking can reduce significantly the dislocation density within the kink bands (KBs) and occasionally turn the local crystal to soft orientation, leading to softening. At low strain rate, kinking predominantly occurs in grains with high Taylor factor values (hard orientation, such as < 110 > or < 111 >//compression direction), exhibiting notable orientation dependency. With increasing strain rate, kinking may activate in soft-oriented grains, while in hard-oriented grains, KBs form clusters with multiple types, sometimes with secondary KBs developing within primary KBs, indicating higher kinking activation and reduced orientation dependency.

Selecting a reasonable mesoscopic contact model and corresponding contact parameters is a key problem in discrete element simulation. In order to characterize the mesoscopic contact characteristics between particles in cohesive soil–rock mixture (CSRM), a set of laboratory consolidated and undrained triaxial tests were conducted on remolded samples of clay and CSRM collected in situ. Based on the experiments, 2D discrete element models of clay and CSRM were established, respectively. Considering the difference in the mechanical characteristics between soil particles and between soil and rock particles, different types of contact model were applied. The effects of the contact stiffness, bond strength, and friction coefficient between soil particles and between soil and rock particles on the stress–strain curves of both clay and CSRM numerical samples were sequentially studied by parameter sensitivity analysis. Results show that the contact stiffness and friction coefficient between soil particles affect the initial tangent modulus, the peak stress and the post-peak residual stress of the clay sample, while the bonding strength only affects its peak stress and residual stress. However, the mesoscopic contact parameters between soil and rock particles have little effect on the initial tangent modulus of CSRM sample but have a certain impact on the development of stress in the plastic stage, among which the influences of normal bonding strength and friction coefficient between soil and rock particles are more obvious. Finally, according to the comparison between the laboratory test results and the corresponding numerical simulation results in both clay and CSRM samples, mesoscopic contact parameters in CSRM were calibrated.

In reduced-activation ferritic-martensitic (RAFM) steels, Cr and Si addition always induced formation of S-ferrite, a soft phase randomly distributed in tempered martensite matrix. Two types of heterogeneous 12Cr1.45Si steel (as a RAFM steel) samples were prepared in this study, with fiber-like S-ferrite embedded in harder or softer tempered martensitic matrix, designated as T600 and T750 respectively. Both samples exhibited excellent strength-ductility synergy compared to conventional RAFM steels and some oxide dispersion-strengthened (ODS) steels. T600 achieved a high tensile strength of 1218 MPa with a total elongation of 20.2 %; T750 displayed 902 MPa with a higher elongation of 38.4 %. The synergy arises from a hetero- deformation-induced (HDI) strengthening mechanism. Additionally, fiber-like S-ferrite aligned along the rolling direction (RD) induces grain boundary delamination, enhancing ductility furtherly.

Grouting reinforcement method is one of the effective methods commonly used in slope reinforcement. At present, grouting reinforcement technology is mostly aimed at sandy soil and clay, and the research on gravel soil is still relatively few. At the same time, because of the strong concealment of slurry diffusion in grouting reinforcement, the process and law of slurry diffusion in grouting process has always been a difficult problem. In this paper, through numerical simulation analysis and indoor simulation grouting test, the law of slurry diffusion flow in slope gravel soil grouting is analyzed, and compared with the law of slurry diffusion in sand. At the same time, the pressure distribution along the slurry diffusion process and the changes of soil parameters before and after grouting are also analyzed. The results show that the final diffusion radius of slurry is proportional to the water-cement ratio and grouting pressure of cement slurry, and the diffusion radius of slurry in slope gravel soil is much larger than that in sand. In slurry diffusion, the pressure along the road gradually attenuates with slurry diffusion, and its attenuation rate is inversely proportional to the water-cement ratio of cement slurry. The attenuation rate in slope gravel soil layer is much slower than that in sand layer. After the slope gravel soil layer and sand soil layer are strengthened by grouting, the porosity of the soil layer decreases and the compressive strength increases. The research results indicate the diffusion law of grouting slurry in slope gravel soil and provide reference for similar engineering designs.

This study presents an energy dissipation analysis approach for cavity expansion problems in crushable granular materials under the high stress state. By assuming that the energy dissipation generated from cavity expansion is mainly absorbed by the volume strain deformation in the plastic region, the energy conservation equations of the volume changes and energy dissipation in the plastic region during cavity expansion are reconstructed based on the compression failure mechanism. The limit pressure of the cavity expansion under high stresses is obtained based on a new critical state line for the crushable granular materials and the energy dissipation analysis method. The proposed approach is validated by the existed results. The effects of the initial void ratio and stress for the crushable granular materials on limiting expansion pressure of cavity expansion are investigated particularly. The results show that the effect is proved to be significant and must be considered in the analysis of cavity expansion problems, particularly for crushable granular materials at high stress.

The hot deformation behavior of FeCrAl–ODS alloys at temperatures of 1050–1200 °C and strain rates of 0.001–1 s−1 was investigated. The peak stress of FeCrAl–ODS alloy during hot deformation decreased with increasing temperature and decreasing strain rate. In addition, the stress–strain curves show a dynamic softening phenomenon according to the shape of the flow curves. Based on the Arrhenius-type model, a constitutive equation and processing map of FeCrAl–ODS alloy were established. Thereafter, we proposed optimum processing parameters of 1200 °C and 0.001 s−1 based on the processing map. Compared with FeCrAl alloys, there was no significant phenomenon of grain coarsening during hot deformation in FeCrAl–ODS alloy. In the electron backscattered diffraction images, both recrystallized and recovered grains were observed in the matrix under different deformation conditions. The fraction of dynamically recrystallized grains in the matrix under the deformation of 1100 °C/0.001 s−1 (42.5%) was significantly higher than that at 1200 °C/0.001 s−1 (10.6%), which was consistent with the stress–strain curves.

高级氧化技术(AOPs)广泛应用于不同的废水处理,并目前此类技术多以羟基自由基(OH·)的产生为主.近年来,基于硫酸根自由基(SO4-·)的AOPs因其对有机污染物的高反应活性和对复杂环境基质的高选择性而备受关注.但是,在对各种活化方式的系统比较方面还存在一些不足,对降解途径和不同阴离子对体系的影响也缺乏研究.本文通过两种染料的降解对3种活化过硫酸盐体系进行了系统性的比较,并结合自由基捕获实验(甲醇,叔丁醇)和产物分析,研究了体系降解机制及路径.研究了4种阴离子(HCO3-、NO3-、Cl-、Br-)对3种不同活化过硫酸盐体系降解染料的影响.结果表明,SO4-·与OH·在3种活化体系中对染料降解均有贡献.在热活化体系(heat-Na2S2O8)中,对染料降解起到主导作用的活性物种为SO4-·;在光活化体系(hv-Na2S2O8)中,对染料降解起到主导作用的活性物种为SO4-·与OH·;而在亚铁离子活化体系(Fe2+-Na2S2O8)中,OH·对染料降解起主导作用.本文以热活化过硫酸盐体系为代表,探索了亚甲基蓝和甲基橙的降解中间体及路径.在3种活化过硫酸盐体系中,4种阴离子在不同程度上对两种染料的降解均存在抑制作用,尤其在亚铁离子活化过硫酸盐体系中,对4种阴离子的浓度变化更为敏感.

Iron-chromium-aluminum (Fe-Cr-Al) alloys have great potential application as an accident-tolerant fuel cladding material in light-water reactors. It has excellent processing ability, resistance to steam oxidation at high temperatures (HTs), and irradiation swelling-resistance. It is necessary to improve the room- and hightemperature mechanical properties and reveal the strengthening mechanism. In this study, we analyzed the effect of Zr on the microstructure and room- and high-temperature tensile properties of hot- and warm-rolled FeCrAl alloys. The results show that the Laves phase could be effectively stabilized by Zr addition, and the proportion of low-angle grain boundaries increased. Moreover, the yield strength at room and high temperatures of the samples after Zr addition were improved, owing to the precipitation and sub-grain boundary strengthening by Zr. In addition, Zr changed the grain orientation, but had no relevance to the number of easier activated slip systems. The movable dislocation cannot slip during high-temperature tensile tests because of the pinning effect of the dynamic precipitated Laves phase, which could be the reason for the decrease in elongation at high temperatures.

This study investigates the coarse Laves phase stimulated nucleation of recrystallization behavior in iron--chromium-aluminum (Fe-Cr-Al) alloys. The results reveal that the samples with coarse Laves phases in the matrix have finer grains because of the occurrence of particle stimulated nucleation (PSN). Due to the lower diffusion coefficient and lower solubilities of Zr in the bcc matrix, Zr addition increases the proportion of the coarse Laves phase, which promotes the PSN, resulting in a fine grain size in the Fe-Cr-Al alloys. The ultimate tensile strength of the Zr-modified Fe-Cr-Al sample with coarse Laves phases in the matrix reaches-600 MPa, and the elongation is up to-28%. Additionally, the high elongation of this sample could greatly improve its formability. The superior combination of strength and ductility is attributed to grain refinement and discon-tinuous deformation. This study could be expected to provide a better understanding of the coarse Laves phase, such as accelerated recrystallization behavior and beneficial effects on the mechanical properties, and provides potential freedom for further design and microstructure control of Fe-Cr-Al alloys.

Using the classical (linear) Mohr-Coulomb (M-C) failure criterion, the failure mechanism of slopes is commonly treated as a completely shear failure. However, the tension failure mechanism has also been commonly observed in landslides, especially for those covered by cemented soils geometrical. Considering only the shear failure would overestimate the tensile capacity of geomaterial, which can lead to an optimistic result. In this paper, a modified M-C failure criterion with zero or low tensile strength (tension cutoff) was introduced that can characterize the shear-tension failure feature of slopes well. Combined with the limit upper bound theory, the expressions of stability factor (N-s) for slopes were derived considering (1) only soil self-weight; and two external conditions, (2) surcharge load, and (3) seismic load. Further, a detailed parametric analysis was conducted. The results show that the slope stability was greatly influenced by the surcharge coefficient (q(t)) and the horizontal seismic acceleration coefficient (k(h)). The influence of the degree of tension cutoff (zeta) on the slope stability strongly depends on the values of slope angle (beta) and internal friction angle (phi). The difference in N-s under two extreme cases (zeta = 0 and zeta = 1) was significant, and the difference was more pronounced with the introduction of surcharge and seismic load.

Collecting morphological characteristics of rock joint surfaces and building a digital rock joint library with abundant sample types and sufficient sample numbers is important for fractured rock mass analysis. To solve the “inflexible field operation” problem in existing contact type and non-contact type data collection procedures, this work presents a photogrammetric workflow in the field for the construction of a 3D rock joint surface database. Innovations in some steps make it practical for field scenarios: image collection procedures in the field and post-processing steps of the SfM-MVS-derived dense point cloud. The performance is considered as good as that of white light scanning, and sub-millimetre accuracy is achieved during batch processing. Two rock joint databases containing 310 samples are established, and two application examples show very good potential of the proposed photogrammetric workflow in the evaluation of rock joint roughness and rock joint anisotropy.

目的 探讨LBL-TBL-翻转式教学法模式的设计及其应用于骨科教学中的效果.方法 选取2018年6月1日—2019年5月30日来医院骨科进行实习的学生80名进行随机分组,每组各40名,由两个独立的教室分别进行授课,即传统教学组和联合教学组,分别实施LBL模式教学和LBL-TBL-翻转式教学法模式教学,并对相应教学指标进行统计分析.结果 联合教学组学生对理论知识、临床技能、诊疗思路、教学效果、阶段考核的评分明显优于传统教学组,组间数据对比分析具有统计学意义(P<0.05);联合教学组学生对教学信息清晰明确、增强师生互动和学习积极性、提高专业知识点掌握程度、提高临床技能操作掌握程度、提高诊断疾病思维和方法能力、对教学满意度的评分及总分高于传统教学组,组间数据对比分析具有统计学意义(P<0.05).结论 LBL-TBL-翻转式教学法模式是一种系统、具体、适应性强、简单易行的骨科学教学模式,可明显提高授课效果和人才培养质量.

Aim at the different typical failure modes of reinforced retaining wall, the corresponding limit state equations were established respectively. Based on the Checking Point method and Monte Carlo method, combined with the engineering examples, the reliability and failure probability were obtained by calculation program. On this basis, the correlation of several key factors influencing the engineering stability was analyzed, and then put forward the corresponding engineering improvement measures. The results showed that the internal stability of reinforced retaining wall (tensile and anti-uplift of reinforced materials) is the key index in reliability analysis; in a large range, the anti-uplift reliability index and the vertical distance from the reinforcement strip to the wall top are basically inverse proportion; the anti-uplift reliability index of the reinforcement strip in wall toe is minimum, so that it is the key index; it must be noticed in calculation that the tensile reliability index of the reinforcement strip present to the middle range of the retaining wall. The smaller the vertical interval, the greater the reliability index of geotextile tensile and anti-uplift; but the greater the vertical density, the worse the economy, thus should seek the balance of safety and economy.

ABSTRACT High-iron content manganese ore resources are becoming the mainstream raw ores for manganese extraction due to the depletion of high-grade manganese ores. Our previous research has reported the optimization parameters for the sintering of high-Fe manganese ore (abbr. high-Fe Mn-ore) fines. This study further investigated the consolidation behavior of high-Fe Mn-ore sinters with natural basicity. Sintering pot tests showed that the high-Fe Mn-ore sintering required high coke breeze dosage (about 9.9 wt.%). The CO content of the outlet flue gas (7.5 vol.%~8.0 vol.%) in the high-Fe Mn-ore sintering was higher than that in the ordinary iron ore sintering (1.0 vol.%~2.2 vol.%). XRD and SEM-EDS analyses indicated that the major mineral phases in the sinters included Fe-Mn oxides (FexMn3-xO4), ferrotephroite ((Fe,Mn)2SiO4), Ca-,Al-,Mn-,Fe- bearing silicate melts, and a small quantity of hausmannite (Mn3O4) and free quartz (SiO2). Optical microstructure and SEM images showed that the Fe-Mn oxides, Ca-, Al-, Mn-, Fe- bearing silicate melts and ferrotephroite particles are closely interconnected with one another. The formation of Fe-Mn oxides and ferrotephroite were beneficial to the sinter strength. Thermodynamic and phase diagram analyses further demonstrated that the major bonding phases of Fe-Mn oxides and ferrotephroite were easily formed under the strong reductive sintering atmosphere of high-Fe Mn-ores.

Phase equilibria of the Ga-Zr system were investigated by experiment and thermodynamic modeling. In the experimental part, eleven alloys were prepared by melting the pure elements and annealed. Both the as-cast and annealed samples were analyzed by X-ray diffraction, optical microscopy, and scanning electron microscope. The annealed alloys were investigated by differential thermal analysis and electron probe microanalysis. In order to assist the thermodynamic modeling, the enthalpies of formation at 0 K for the GaZr2, Ga3Zr5, Ga2Zr3, Ga4Zr5, alpha GaZr, Ga3Zr2, Ga5Zr3, Ga2Zr and Ga3Zr phases were computed via first-principles calculations. The enthalpy of formation at 298 K for the alpha GaZr was measured by high temperature reaction calorimetry. Based on the experimental phase diagram data from the present work and the literature as well as the present first-principles calculations, the Ga-Zr system was critically assessed by means of CALPHAD approach. The calculated phase diagram and thermodynamic properties agree well with the available experimental data. (C) 2013 Elsevier B.V. All rights reserved.