Crystal defects are critical in the microstructure control of titanium alloys, as they determine the precipitation characteristics of alpha phase. In this study, the decomposition of stress-induced martensite in Ti-10V-2Fe-3Al is investigated to understand the effect of martensite on alpha precipitation. The crystallography between alpha and beta phases is analyzed using Electron Backscatter Diffraction (EBSD) and Transmission Electron Microscopy (TEM). During decomposition, the martensite is first transformed into alpha, and then to beta(T), with a misorientation of 50(degrees)/ <110> with matrix beta(M). During further aging, alpha begins to precipitate at the beta(M)-beta(T) boundaries, and alpha phase exhibits two types of orientation relationships with beta phase, i.e. Type I: one involving a double Burgers orientation relationship (BOR) and Type II: the other involving a single-sided BOR with beta(T) while the other side follows ((1) over bar 10)beta M similar to ((1) over bar2 (1) over bar3)alpha [(11) over bar1]beta M similar to [(1) over bar 010]alpha with beta(M). As for Type I, the selection of single alpha variant is due to the constraint of the beta grains, < 1<(1)over bar>1>(beta T) and < 1<(111)over bar>>(beta M) are parallel to [(1) over bar2 (1) over bar0](alpha) and [1 (1) over bar 20](alpha) respectively and its habit plane {334} is close to beta(M)-beta(T) boundary. In Type II, the selected alpha variant, which has a {334} habit plane, also lies close to the beta(M)-beta(T) boundary. This finding indicates that the variant selection rule of the habit plane governs alpha precipitation during martensite decomposition.

Lightweight refractory high- and medium-entropy alloys (LRH/MEAs) are being explored as potential materials for lightweight applications owing to their low densities, high strengths, and excellent strengthto-weight ratios. However, their limited ductility and formability under ambient conditions restrict their broad industrial applications, particularly in the manufacturing of highly valuable, hot-sectional parts with complex geometries. Although recent studies have advanced the understanding of ductilization in these alloys, practical solutions to overcome the ambient ductility and formability limitations remain elusive. Here, we report an exceptional superformability in ambient cold-rolling of a strong-yet-ductile Ti50 V29.5 Zr10 Nb10 Mo0.5 (at. %) LRMEA, achieving a remarkable elongation of 1600 % at a thickness reduction of 96 %, without the need for intermediate stress-relieving annealing. The observed superformability arises from the adaptive buffering microstructures that evolve during the cold-rolling process, namely, slip and kink bands in the early stage, kink and shear bands in the moderate stage, and shear bands and dislocation channels in the late stage. These localized microstructures act as adaptive stress buffers, effectively mitigating stress concentrations, and thereby preventing crack initiation and propagation. After cold-rolling annealing at 400 degrees C for 1 h, the 0.2 mm-thin LRMEA strip reaches an ultrahigh yield strength of 1.5 GPa while maintaining a sufficient elongation of 10 %. These findings demonstrate that the engineering of stagewise adaptive microstructural buffers is a promising strategy for mitigating stress concentrations and achieving superior performances. This strategy can be utilized in the future design of ductile, superformable refractory alloys, such as LRH/MEAs, with potential applications in engineering sectors that require high-strength, lightweight thin strips. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Precipitation strengthening is a common way to strengthen metallic materials, where the effectiveness depends on the morphology, size, fraction of the precipitates, etc. The precipitation process is significantly influenced by crystal defects like dislocations and grain boundaries, which act as nucleation sites. However, the understanding of the transformation crystallography at interphase boundaries is limited. In this study, the precipitation crystallography of α phase on the stress-induced martensite in Ti–16V–4Sn was studied by scanning electron microscope (SEM) and electron backscatter diffraction (EBSD). Stress-induced α″ martensite is produced by uniaxial compression of solution-treated alloy and maintains an orientation relationship with the β matrix (βM), i.e., ( 110)_β //( 001)_α^'' ,[ 1 - 10]_β //[ 100]_α^'' or ( 110)_β // ( 001)_α^^'' , [ 1 - 10]_β // [ 110]_α^^'' . Subsequent aging resulted in a sandwich-like microstructure (βM–α–βT), where the film-like α phase precipitated on the boundary of martensite continuously, and the martensite reversed to β phase (βT) before α precipitation, which held the orientation of 50–60°/<110> with βM. The precipitated α on the martensite boundary held Burgers orientation relationship (BOR), i.e., (110)β // (0001)α, [1–11]β // [11–20]α with both βM and inside βT, respectively. The observed misorientation angle of 50°–60° and the transformation crystallography of α phase are rationalized by transformed variants.

你是否想过,一把生锈的古剑背后,可能藏着千年前的锻造技艺?冶金考古,正是通过科学方法"阅读"金属文物中的微观信息,还原古代工匠的智慧;而一种名为"电子背散射衍射(EBSD)"的现代分析技术,已发展成为该领域的一项关键分析工具.EBSD技术能够精准识别金属中微米级的晶体结构、取向和相组成,甚至能"反推"出古代材料在高温下的原始状态.这不仅帮助考古学者更准确地判断铁器的冶炼与热处理工艺,还为材料科学与工程的教学提供了生动而深刻的实例.本文基于北京科技大学在科技史与材料科学领域的积累,通过多个出土铁器的真实案例,展示EBSD技术如何揭示以往难以察觉的微观信息.同时,笔者结合多年教学经验,系统阐述了如何将EBSD数据融入《材料科学基础》课程的教学改革中,从教材编写、实验设计到课外拓展,全面增强学生对材料微观世界的理解.EBSD技术不仅是传统金相法的重大升级,更是连接古代工艺与现代材料科学的重要桥梁.让我们一起走进这场科技与历史对话的新时代.

This study employs molecular dynamics simulations to analyze the crystal structure, lattice rotation, dislocations, twinning, shear strain, and volumetric strain in three copper workpieces during the equal channel angular pressing (ECAP) process. The workpieces, oriented as [100], [110], and [111], are aligned parallel to the Y-axis in the simulation, corresponding to the extrusion direction. The deformation of the three workpieces is primarily achieved through the interaction between twinning and dislocation slip. The [100] oriented workpiece activated multiple slip systems with high shear factors, leading to intense shear deformation. This caused different regions to experience varying strains, resulting in the most dispersed lattice rotation distribution. The intense deformation also generated the most deformation twins, and the interaction between deformation twins and dislocations was the strongest, further increasing the overall dislocation density, thereby causing the most severe grain fragmentation. The [111] oriented workpiece activated only one slip system, causing minimal shear deformation, fewer dislocation interactions, and uniform deformation. The deformation and grain fragmentation of the [110] oriented workpiece were intermediate between the other two orientations. This research provides theoretical insights for optimizing the ECAP process and enhancing copper performance.

The thinning is a trend in the development of high-end electrical steel.Although its iron loss can be further reduced,the larger cold rolling reduction and the surface effect can influence the microstructure and texture of the final product,thereby affecting the magnetic properties.The two-stage cold rolling method can optimize the texture and increase the proportion of{100}and Goss textures.The influence of processing parameters on the microstructure,texture,and magnetic properties of a 0.10 mm thick ultra-thin non-oriented electrical steel is investigated by the two-stage cold rolling method,with a focus on the role of surface effects during prolonged holding.The results show that cube and Goss textures coexist in the final sheets produced by the two-stage cold rolling method.Furthermore,when the combined reduction from the two stages falls within the range of approximately 75%to 81%,the resulting texture and magnetic properties are superior to those of samples with reduction combinations of 90%/50%and 50%/90%.Within the temperature range of 840-920℃,the influence of time on grain growth is greater than that of temperature,and grain growth is affected by the surface effect in all cases.During isothermal annealing at 920℃,the 0.1 mm thick sample exhibits a more significant surface effect compared to the 0.27 mm thick sample,meaning grain growth is significantly hindered;the average grain size after the annealing for 60 min could not exceed the sheet thickness of 100 μm.In contrast,the average grain size of the 0.27 mm thick sheet grows to 175 μm.

thinning is a trend in the development of high-end electrical steel. Although its iron loss can be further reduced, the larger cold rolling reduction and the surface effect can influence the microstructure and texture of the final product, thereby affecting the magnetic properties. The two-stage cold rolling method can optimize the texture and increase the proportion of {100} and Goss textures. The influence of processing parameters on the microstructure, texture, and magnetic properties of a 0.10 mm thick ultra-thin non-oriented electrical steel is investigated by the two-stage cold rolling method, with a focus on the role of surface effects during prolonged holding. The results show that cube and Goss textures coexist in the final sheets produced by the two-stage cold rolling method. Furthermore, when the combined reduction from the two stages falls within the range of approximately 75 degrees o to 81 degrees o, the resulting texture and magnetic properties are superior to those of samples with reduction combinations of 90 degrees o /50 degrees o and 50 degrees o / 90 degrees o. Within the temperature range of 840-920 degrees C, the influence of time on grain growth is greater than that of temperature, and grain growth is affected by the surface effect in all cases. During isothermal annealing at 920 degrees C, the 0.1 mm thick sample exhibits a more significant surface effect compared to the 0.27 mm thick sample, meaning grain growth is significantly hindered; the average grain size after the annealing for 60 min could not exceed the sheet thickness of 100 mu m. In contrast, the average grain size of the 0.27 mm thick sheet grows to 175 mu m.

Si3N4 ceramics are highly valued for their exceptional thermal conductivity and mechanical properties. This study investigated the effects of different addition ratios of Y2O3-MgO-MgSiN2 ternary sintering additives on liquid phase viscosity, densification, microstructure, thermal conductivity and mechanical properties. The incorporation of MgSiN2 as sintering additives introduced additional Si and N into the liquid phase, forming a nitrogen-rich liquid phase that promoted the grain growth showing a bimodal distribution. When the MgO/ MgSiN2 ratio reached 2/3, the moderate liquid phase viscosity facilitated enhanced densification and grain growth. This resulted in an increased number of large grains, a moderate grain size distribution, and a good bimodal microstructure. Consequently, the 2M3N exhibited superior properties, including a thermal conductivity of 105.22 W m-1 K-1, a fracture toughness of 5.91 MPa m1/2, and a bending strength of 726.12 MPa. The study demonstrates that precise control of the Y2O3-MgO-MgSiN2 ratio can effectively regulate the microstructure, leading to improved thermal and mechanical performance.

Adding carbon nanotubes (CNTs) to metal composites changes their corrosion resistance, which is significantly affected by the distribution of CNTs. In this study, the effect of the content and distribution of CNTs on the corrosion resistance of composites was investigated by changing the electrodeposition process. The results indicated that could inhibit grain growth and act as an elemental channel for passivation film formation, which positively enhanced the corrosion resistance of the material. However, the annealing used to improve the bonding strength of CNTs to the matrix increased the grain size of the material, which had a weakening effect on the corrosion resistance. Using ultrasonic in electrodeposition had an obvious promoting effect on the uniform distribution of CNTs. The composites with 0.1 g/l CNT showed the best corrosion resistance after annealing for 30 min at 600 °C.

The presence of island grains in the initial finished sheets of grain-oriented electrical steel is inevitable in the preparation of ultra-thin strips. Owing to their distinctive shape and size effects, their deformation behavior during rolling differs from that of grain-oriented electrical steels of conventional thickness. This study focuses on the orientation evolution and deformation heterogeneity of island grains during rolling. Four types of island grains with orientations of {210}<001>, {110}<112>, {114}<481>, and {100}<021> were selected and modeled within the Goss-oriented matrix using full-field crystal plasticity finite element (CPFEM) simulation under plane strain compression. The results are then compared with corresponding experimental measurements. The results reveal that orientation rotation and grain fragmentation vary among the island grains of different orientations, with the first two orientations exhibiting more significant deformation heterogeneity compared to the latter two. Additionally, the orientations of the island grains significantly affect the distribution of residual Goss orientations within the surrounding matrix. Pancake-like island grains exhibit a higher degree of orientation scatter and greater deformation heterogeneity in the central layer compared to their spherical counterparts. The initial {210}<001> island grains can form a cube orientation, which can be optimized by subsequent process control to enhance magnetic properties.

基于笔者从事织构研究及课程讲授织构概念的背景,对一张柯俊先生早年参加全国织构会议的照片进行了分析,讨论了 3个学会共同组织第一次国内织构会议的目的、意义及柯先生和老一代织构研究学者的贡献,分析了其课程思政的作用.此外,本文分析了织构基本含义,学生理解时面临的困难及克服的方法,织构研究的历史及涉及的范围.最后,从一流课程建设的角度分析了"两性一度"教学要求下讲授织构知识点的方式与方法,并与柯先生"大材料"试点班的教改理念进行了比较,提出了将织构知识点凝练成体现课程"两性一度"特点的案例设想与方法.

The hot‐rolled sheets of low‐grade electrical steels undergo complete austenite‐ferrite phase transformation, resulting in fine equiaxed grains in the sheets. These fine initial grains eventually lead to a strong detrimental {111} texture in the final product after cold‐rolling and annealing process. This work, based on the phase transformation delay of columnar grain structure in cast slabs, proposes a novel approach called metastable ferrite hot rolling, namely, a two‐stage heating at 900 °C and then at 1100 °C shortly and hot rolling, to avoid complete transformation and to retain original {100} oriented regions. In addition, low‐temperature annealing is employed to increase grain sizes of hot‐rolled sheets thereby improving the final texture and magnetic properties after cold‐rolling and annealing. The results indicate that metastable ferritic columnar grains can be maintained during the two‐stage heating process at 1100 °C and primarily undergoes subgrain growth. The transformation from ferrite to austenite at 1100 °C is very slow. During the hot rolling with a high 86% reduction by two passes, the notable grain refinement is mainly caused by dynamic recrystallization rather than dynamic phase transformation as evidenced by the observation from the rolling plane.

In situ X-ray synchrotron microtomography was used to quantify the evolution of damage in the titanium alloy Ti5321 with bimodal microstructure. The results show that voids nucleate in the equiaxed primary alpha grains and alpha plates or at alpha/beta interfaces. There exists an approximate linear relationship between volume of voids and local strain of several largest voids. The low growth rate and delay of coalescence of voids are attributed to the dispersed distribution of the alpha phase in the bimodal microstructure. There are no micro-cracks formed in the interior of the sample until fracture. The deep dimples in the fracture surface indicate ductile fracture. The damage mechanism of Ti5321 is discussed with the help of post-mortem SEM. To clarify the difference in damage mechanism between metastable beta and alpha + beta titanium alloys, Ti64 is also in situ tensile tested.

Micromechanical problems seek full-field solutions in response to external and/or internal thermal-mechanical loads, which have been increasingly encountered in material property and process assessments. Here we present a machine learning based strategy of solving micromechanics at finite strains. Deep neural networks (DNNs) are trained by employing the elastic energy together with other physical constraints to formulate the loss function. In particular, the crossover of material points, which can be a common issue for similar DNNs when applied to compression-dominant problems, is shown to be effectively addressed by including a kinematic penalty term that forces the DNN to maintain structural integrity and stability and avoid unphysical behavior. The generality and accuracy of the proposed physics-driven neural networks (PDNNs) is demonstrated through various micromechanical problems, including single crystal anisotropy elasticity, Eshelby's inclusion problem, buckling, and elastic homogenization of polycrystals. The effect of the choice of optimizers and hyperparameters on the PDNN training are discussed and the computational efficiency is also analyzed. It is shown that this novel PDNN framework can completely remove the need of labeled training data and exhibit improved performances as compared to the conventional physics-informed neural networks (PINNs) in terms of avoiding unphysical solutions and attaining higher computational efficiency. PDNNs can thus serve as a promising tool to solve some critical challenges associated with a wide range of nonlinear micromechanical problems.

To weaken texture and homogenize microstructure, the evolution of microstructure and texture of large-sized metastable β-titanium alloy Ti55511 in industrial scale during multiple rounds of forging was studied by electron backscatter diffraction. The forging process, including alternate upsetting and stretching was used. However, the microstructure and texture change much from the center to the edge of the large-sized bar after different forging passes. The volume fraction of α increases from the center to the edge of the sample, and with decrease in forging temperature. The spherical α phase forms until the ninth forging pass. The texture characteristics are basically fixed in the first forging pass in (α + β)-phase (the fourth pass). The texture of the sample after forging passes is characterized by the formation of <001> fiber at the edge of the sample. In the center of the large-sized bar, there are strong <110> and <111> fiber textures after the fourth pass. The volume faction of <100> fiber texture keeps increasing trend from central areas to areas at the edge, whereas the <110> fiber texture keeps decreasing trend from central areas to areas at the edge from the fourth pass.

In this paper, the effects of sodium dodecyl sulfate (SDS) concentrations in the electroplating solution on the morphology, nucleation rate, nucleation mode, and frictional behavior of the CNT/Ni composite layers were investigated. The results showed that the electrodeposition of Ni was in a three-dimensional nucleation/growth mode. In addition, the x-ray diffraction (XRD) of the deposited layers showed that adding SDS changed the preferred growth direction of Ni from (2 0 0) to the (2 2 0) crystallographic plane. When the carbon nanotube (CNT) content was 0.1 g l ^−1 , and the SDS content was 0.05 g l ^−1 , the deposition potential was the most negative, increasing the number of Ni nucleation sites on the electrode and resulting in the grain size refinement of the deposited layer. It also reduced the friction coefficient of the composite simultaneously.

Most of the electrical steel slabs are composed of {100} columnar grains. After hot rolling, there is a texture gradient across the thickness. The surface shear textures (Goss texture{110}<100>, Brass texture{110}<112>, Copper texture{112}<111>) and certain <001>//ND fiber textures after hot rolling can be inherited into the finished sheet. The volume fraction and distribution of these textures after cold rolling significantly influence the magnetic properties. Therefore, a full-field crystal plasticity finite element method (CPFEM) was employed to simulate the evolution of microstructure and orientations of {100} columnar grains under plane strain compression and an additional displacement gradient component L (13) . Through qualitative and quantitative analysis of the simulated microstructure, it was found that under plane strain compression, {100}<110> grains were the most stable, followed by {100}<001> grains. Nearly {100}<021> orientation rotated towards {114}< 481> orientation at the extremities of the simulation block. The additional displacement gradient component L- 13 enhanced the rotational effect. At the 45 (degrees) shear direction and ends of the simulation block, the {110}<110> orientation originated from {100}<001> grains, the nearly {110}<112> orientation formed from {100}<021> grains, and the {112}<111> Copper orientation derived from {100}<110> grains. However, the simulation did not demonstrate the development of Goss shear orientation.

By hot rolling Fe-2.5% Si-0.8% Al electrical steel slabs to total reductions of 52% and 88%, respectively, the formation of shear textures (Goss texture{110} < 100 > , brass texture{110} < 112 > , copper texture{112} < 111 > ) with 52% reduction and the retention of {100} textures (cube texture{100} < 001 > , 25° rotated cube texture{100} < 021 > , rotated cube texture{100} < 110 > ) with 88% reduction were analyzed. The results indicated that the orientation rotation of the initial grain in the surface layer region at 52% reduction only slowly approached the three orientations of the shear type texture. The reasons included many influencing factors, such as the coarse grain sizes, the interaction of surrounding grains, and the deviation of initial orientations to ideal < 001 > //ND orientations. The orientation rotations at 52% reduction were not as typical as at the large hot-rolling reductions. In addition, large regions of cube and 30°-rotated cube orientation could be retained in the central layer at 88% reduction. These phenomena were clearly different from the cold-rolling behavior of columnar grains. Compared with the central layer of industrial hot-rolled sheets, it was found that the < 001 > //ND fiber textures of laboratory hot-rolled sheets were retained more easily.

Compared with high-grade electrical steel, low-grade electrical steel has the advantages of low cost and high production quantity but low profits. Therefore, researchers often focus on studying high-grade electrical steel without phase transformation. The microstructure evolution of low-grade electrical steel is more complicated compared to high-grade steel due to the three transformation stages- casting, hot rolling, and final annealing-that are present between austenite and ferrite during their processing. During continuous casting, the <100> columnar grains commonly formed in the low-grade electrical steel cast slabs with phase transformation illustrate the characteristics of the pronounced transformation delay and suppression. In such conditions, the change in hot rolling temperature will cause diversity in hot-rolled microstructures and textures and affect the subsequent cold rolling and annealing microstructure and texture. Based on the previous studies on the effect of hot rolling processes on the transforma-tion texture of industrial low-grade electrical steel and the observation of the transformation delay and suppression of columnar grains in cast slabs, this work further investigates the influence of the initial microstructures before cold rolling and cold rolling reduction on the transformation texture and explores the law of texture inheritance. In particular, the idea of retaining {100} texture using metastable ferrite hot rolling is proposed to improve magnetic properties. The results show that there are more {100} deformed grains in the hot-rolled plate heated at low temperature, and the {100} texture inheritance is obvious after cold rolling and transformation annealing, which effectively improves the magnetic properties. The {100} transformation texture is weakened with the increase in rolling reduction because the initial {100} grains gradually disappear with increasing rolling reduction. An analysis shows that although the {100} transformation texture induced by the surface effect is hindered by the alloying Al and P elements in the used industrial electrical steel, the favorable initial {100} texture produced using low-temperature hot rolling promotes the memory-type transformation texture. In addition, the transformation texture obtained at a high annealing temperature is still better than the recrystallization texture obtained at a low annealing temperature. The significance of these results lies in the possible future practice of enhancing {100} texture in hot rolled plate by metastable ferrite rolling to improve magnetic properties in final annealed sheets.

鞍钢被称为共和国钢铁工业的长子,它为很多新中国成立后新建的钢铁企业输入了大量人才和技术,做出了重要贡献.鞍钢还产生了很多全国劳动模范,成为全国人民学习的榜样.作为北京科技大学(前北京钢铁工业学院)材料科学基础课程任课教师,有幸参与了十余年鞍钢的科研活动,在课程知识应用、钢铁企业人文历史传承方面都有很多感受;也融入并见证了我国取向硅钢由引进国外技术到自主开发并处于国际先进水平的过程.本文从任课教师的角度,讨论了笔者作为教师及科研人员参与鞍钢硅钢开发的一些感想,尝试通过自身感受讲授课程知识应用、寻找课程思政元素,以提升授课效果;讨论了作为教材经典内容的二次再结晶理论的变迁所导致的修改教材、开发新实验的可能性.