Materials Science and Engineering: A最新文献_第3页

High-performance on-line repair of subsea pipeline steel via underwater direct metal deposition: Microstructure evolution and mechanical properties 水下直接金属沉积水下管道钢的高性能在线修复：组织演变和力学性能

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-09 DOI: 10.1016/j.msea.2025.149592

Zhandong Wang , Chunke Wang , Linzhong Wu , Zhiyuan Jia , Mingzhi Chen , Huifang Lan , Guifang Sun

Underwater direct metal deposition (UDMD) is a promising technique for the on-line repair of subsea pipeline steel. However, the influence of special underwater thermal cycles, involving laser heating and water cooling, on microstructure and properties remains unclear. In this work, simulated defects on an X70 steel plate are repaired using UDMD at a water depth of 30 m. Defect-free repaired zone with sound metallurgical bonding to the substrate is obtained. The special thermal cycles lead to spatially heterogeneous microstructures across deposition layers. Rapid solidification in the first layer promotes the formation of lath bainite. As layer numbers increase and heat accumulates, the solidified microstructure transforms into acicular ferrite and polygonal ferrite. Blocky-type M/A constituents are formed within the grains due to the water cooling effect. However, subsequent thermal cycles decompose the M/A constituents into rod-like carbides. The UDMD X70 exhibits a trade-off between strength and toughness. The yield strength of the repaired plate is 12.6 % higher than that of the substrate, while the elongation of the repaired plate is decreased by 45 %. The fine grain structure (3.1 ± 0.5 μm) and high dislocation density ((4.5 ± 0.4) × 10¹⁴ m⁻²) in the repaired zone account for the high yield strength and reduced ductility. The absorbed energy of the repaired plate (20 ± 2 J) is significantly lower than that of the substrate (263 ± 10 J) at −40 °C. The microstructural heterogeneity, hard/soft region mismatch, and high dislocation density in the repaired zone facilitate the brittle cleavage fracture of the repaired X70. These findings underscore the critical influence of underwater thermal cycles on microstructure evolution and mechanical properties, directly affecting underwater joint integrity.

水下直接金属沉积（UDMD）是一种很有前途的海底管线钢在线修复技术。然而，特殊的水下热循环，包括激光加热和水冷却，对微观结构和性能的影响尚不清楚。在这项工作中，使用UDMD在水深30 m的情况下修复了X70钢板上的模拟缺陷。获得了与基体良好的冶金结合的无缺陷修复区。特殊的热循环导致沉积层间的微观结构在空间上不均匀。第一层的快速凝固促进了板条贝氏体的形成。随着层数的增加和热量的积累，凝固组织转变为针状铁素体和多边形铁素体。由于水冷却作用，晶粒内部形成块状的M/A成分。然而，随后的热循环将M/A成分分解成棒状碳化物。UDMD X70展示了强度和韧性之间的权衡。修复板的屈服强度比基体的屈服强度提高12.6%，而修复板的伸长率下降45%。修复区内细小的晶粒组织（3.1±0.5 μm）和较高的位错密度（（4.5±0.4）× 1014 m−2）是导致材料屈服强度高、塑性降低的主要原因。在−40℃时，修复板的吸收能量（20±2 J）明显低于衬底的吸收能量（263±10 J）。显微组织的非均匀性、硬/软区错配、修复区位错密度高，促进了修复后X70的脆性解理断裂。这些研究结果表明，水下热循环对水下接头的微观结构演化和力学性能具有重要影响，直接影响水下接头的完整性。

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引用次数: 0

Decoupling tensile ductility and fracture toughness in additively manufactured AlCoCrFeNi2.1 eutectic high entropy alloy 增材制备AlCoCrFeNi2.1共晶高熵合金的解耦拉伸延展性和断裂韧性

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-09 DOI: 10.1016/j.msea.2025.149593

Junhao Gao , Yuzhen Yin , Bowen Ma , Jiahang Liu , Kuizhang Li , Dongdong Li , Lv Zhao , Jiahao Yao , Lin Liu , Jie Pan

Eutectic high-entropy alloys (EHEAs) have attracted significant attention due to their excellent strength-ductility synergy under quasi-static tensile loading. This favorable mechanical performance has intuitively led to the assumption that EHEAs also possess high fracture toughness, given their capacity for substantial plastic energy absorption during deformation. In this study, we decouple tensile ductility and fracture toughness in a dual-phase AlCoCrFeNi_2.1 EHEA produced via laser powder bed fusion. Experimental results demonstrate that this EHEA exhibits excellent tensile behavior with a yield strength of 1320 MPa, a tensile strength of 1590 MPa and a uniform elongation of 10.5 %. Paradoxically, this EHEA exhibits a relatively low fracture toughness of 39 MPa m^1/2. Fractographic analysis reveals a largely brittle fracture process, wherein the fatigue pre-crack propagates nearly straight with limited evidence of dislocation-mediated plasticity at the crack tip. Crack propagation is facilitated by microcracks that form at the phase boundaries and coalesce with the main crack along the lamellar direction. This embrittled behavior contrasts sharply with the coordinated deformation observed in both face-centered cubic (FCC) and body-centered cubic (BCC) phases during uniaxial tensile loading. Crystal plasticity simulations under varying stress states reveal that the local stresses within the FCC and BCC phases increase substantially under high stress triaxiality (i.e. with a pre-crack), reaching values approximately four times higher than those under low stress triaxiality condition (i.e. uniaxial tension). Such elevated local triaxial stress impedes dislocation slip across phase boundaries, promoting rapid crack propagation with minimal plastic deformation.

共晶高熵合金（EHEAs）在准静态拉伸载荷下具有良好的强度-塑性协同作用，引起了人们的广泛关注。这种良好的力学性能直观地导致了EHEAs也具有高断裂韧性的假设，因为它们在变形过程中具有大量的塑性能吸收能力。在这项研究中，我们将通过激光粉末床熔合制备的双相AlCoCrFeNi2.1 EHEA的拉伸延展性和断裂韧性解耦。实验结果表明，该EHEA具有优异的抗拉性能，屈服强度为1320 MPa，抗拉强度为1590 MPa，均匀伸长率为10.5%。矛盾的是，这种EHEA的断裂韧性相对较低，为39 MPa m1/2。断口分析揭示了一个很大程度上的脆性断裂过程，其中疲劳预裂纹几乎是直线扩展的，在裂纹尖端有有限的位错介导的塑性证据。微裂纹在相界处形成，并沿片层方向与主裂纹合并，有利于裂纹扩展。这种脆化行为与在单轴拉伸加载过程中观察到的面心立方（FCC）和体心立方（BCC）相的协调变形形成鲜明对比。不同应力状态下的晶体塑性模拟结果表明，在高应力三轴性条件下（即存在预裂纹），FCC和BCC相内的局部应力显著增加，达到低应力三轴性条件下（即单轴拉伸）的约4倍。这种升高的局部三轴应力阻碍了位错滑移跨越相界，促进了以最小塑性变形的快速裂纹扩展。

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引用次数: 0

Y2O3 nanoparticle reinforced H13 tool steel fabricated via electron beam melting: Variant selection, microstructural evolution, and strengthening mechanisms 电子束熔炼制备Y2O3纳米颗粒增强H13工具钢：变体选择、显微组织演变及强化机制

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-09 DOI: 10.1016/j.msea.2025.149600

Jiaqi Deng, Gengjie Wang, Hongjun Qi, Hanyu Ma, Yongxin Jian, Zhifu Huang

H13 tool steel is widely applied in the die industry owing to its excellent thermal strength and wear resistance. However, components fabricated via electron beam melting (EBM) still suffer from unsatisfactory strength–ductility balance. In this study, yttrium oxide (Y₂O₃)/H13 composites were fabricated using EBM with 0.2 wt% Y₂O₃ nanoparticles added to optimize the microstructure and mechanical performance. The results showed that Y₂O₃ nanoparticles suppressed prior austenite grain (PAG) coarsening and promoted heterogeneous nucleation, resulting in finer and more equiaxed grains. The composite microstructure changed from an interwoven martensite–bainite structure to a continuous martensitic matrix with discrete bainitic islands, accompanied by higher martensite content. Furthermore, the refinement of PAGs improved variant selection, increasing the proportion of high-angle grain boundaries and improving crack resistance. Consequently, the Y₂O₃/H13 composite exhibited a yield strength of 1463 MPa, an ultimate tensile strength of 1927 MPa, and a total elongation of 11.8 %, outperforming EBM-fabricated H13 steel in both strength and ductility. Quantitative analysis revealed that the strength improvements primarily resulted from grain refinement strengthening provided by finer grains, dislocation strengthening associated with the high dislocation density, and dispersion strengthening introduced by the added Y₂O₃ nanoparticles. These findings emphasize the importance of ceramic particles in tailoring microstructure to overcome the strength–ductility tradeoff, providing a promising avenue for the development of high-performance advanced tool steel.

H13工具钢因其优异的热强度和耐磨性在模具行业中得到了广泛的应用。然而，采用电子束熔化法制备的构件强度-延性平衡仍不理想。本研究采用EBM制备氧化钇(Y2O3)/H13复合材料，并添加0.2 wt%的Y2O3纳米颗粒，以优化其微观结构和力学性能。结果表明：Y2O3纳米颗粒抑制了先前的奥氏体晶粒粗化，促进了非均质形核，使晶粒更细、更等轴；复合材料显微组织由马氏体-贝氏体交织结构转变为连续的马氏体基体和离散的贝氏体岛，马氏体含量增加。此外，pag的细化改善了变体选择，增加了高角度晶界的比例，提高了抗裂性。因此，Y2O3/H13复合材料的屈服强度为1463 MPa，极限抗拉强度为1927 MPa，总伸长率为11.8%，在强度和延展性方面都优于ebm制造的H13钢。定量分析表明，强度的提高主要来自于细晶粒的细化强化、高位错密度的位错强化以及添加Y2O3纳米颗粒带来的弥散强化。这些发现强调了陶瓷颗粒在调整微观结构以克服强度-塑性权衡方面的重要性，为高性能先进工具钢的开发提供了一条有希望的途径。

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引用次数: 0

Investigation of grain refinement and precipitation strengthening mechanisms in FeNiCoCrTi high-entropy alloy facilitated by trace yttrium addition 微量钇促进FeNiCoCrTi高熵合金晶粒细化和析出强化机制的研究

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-08 DOI: 10.1016/j.msea.2025.149585

Junhong Zhang , Lianning Li , Chunyu Zhao , Lei Zhang

The FeNiCoCr-based high-entropy alloy (HEA), characterized by a FCC crystal structure, exhibits excellent ductility and fracture toughness. However, its initial yield strength is generally relatively low, limiting its wider applicability. To overcome this limitation, the present study employed two primary strategies to enhance yield strength: (1) grain refinement achieved by incorporating varying concentrations of the rare earth element Y, thereby exploiting the Hall-Petch effect to increase yield strength; and (2) precise regulation of Y content to promote precipitate formation, with precipitate strengthening further contributing to yield strength improvement. A series of (Fe₃₀Ni₃₀Co₂₅Cr₁₀Ti₅)_100-xY_x (x = 0, 0.1, 0.3, 0.5 at%) HEAs were synthesized via vacuum arc melting. Experimental results demonstrate that increasing Y content leads to significant grain refinement. Specifically, the average grain size of the (Fe₃₀Ni₃₀Co₂₅Cr₁₀Ti₅)_99.7Y_0.3 alloy was measured at 206.33 μm, representing a 64.82 % reduction compared to the 586.57 μm grain size of the Y-free alloy. Additionally, numerous dislocations and stacking faults were observed near precipitates. Under these conditions, the yield strength reached 408.6 MPa, tensile strength attained 692.2 MPa, and fracture elongation was maintained at 28.11 %, thereby achieving an optimal balance between strength and ductility. The observed enhancement in yield strength is substantial relative to conventional cast FeNiCoCr-based HEAs. In summary, the approaches presented herein provide valuable insights for improving yield strength in FeNiCoCr-based HEAs.

fenicocr基高熵合金（HEA）具有FCC晶体结构，具有良好的延展性和断裂韧性。然而，其初始屈服强度一般较低，限制了其更广泛的应用。为了克服这一限制，本研究采用了两种主要策略来提高屈服强度：(1)通过加入不同浓度的稀土元素Y来实现晶粒细化，从而利用Hall-Petch效应来提高屈服强度；(2)精确调节Y含量，促进析出相形成，析出相强化进一步提高屈服强度。采用真空电弧熔炼法制备了一系列（Fe30Ni30Co25Cr10Ti5）100-xYx (x = 0,0.1, 0.3, 0.5 at%) HEAs。实验结果表明，Y含量的增加导致晶粒细化。其中，（Fe30Ni30Co25Cr10Ti5）99.7Y0.3合金的平均晶粒尺寸为206.33 μm，比无y合金的586.57 μm晶粒尺寸减小了64.82%。此外，在析出相附近观察到大量的位错和层错。在此条件下，屈服强度达到408.6 MPa，抗拉强度达到692.2 MPa，断裂伸长率保持在28.11%，达到了强度与塑性的最佳平衡。与传统的基于fenicocr的铸造HEAs相比，所观察到的屈服强度的增强是实质性的。总之，本文提出的方法为提高基于fenicocr的HEAs的屈服强度提供了有价值的见解。

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引用次数: 0

Hierarchical microstructures in Al-Cr-Fe-Ni multi-principal element alloys via simple change of Cr/Ni ratio for enhanced mechanical properties 通过简单改变Cr/Ni比，Al-Cr-Fe-Ni多主元素合金的组织分层，提高了力学性能

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-08 DOI: 10.1016/j.msea.2025.149594

Peng Yan, Linxiang Liu, Yuhao Jia, Feng He, Junjie Li, Jincheng Wang, Zhijun Wang

The multi-principal element alloys (MPEAs) provide a broader compositional and structural design space for the development of metallic structural materials. In the Al-Cr-Fe-Ni system, subtle changes of composition can induce complex hierarchical microstructures, giving the opportunity to achieve excellent strength-ductility synergy. Here in this work, a series of Al₁₄Fe₂₀Cr_xNi_66-x (x = 6, 9, 12, 15 at.%) MPEAs were designed and prepared by combining the Cr/Ni ratio modulation and thermomechanical treatment. The increasing Cr/Ni ratio triggers a transition from single FCC phase to FCC/B2 dual phase, and the B2 phase pins the FCC grain boundaries to refine grain size. Meanwhile, the increased Cr/Ni ratio alters the volume fraction and size of L1₂ and BCC precipitates on the nanoscale. The obtained multiscale hierarchical microstructure significantly enhances the room-temperature strength, raising the tensile strength from ∼905 MPa to ∼1233 MPa, with a slight reduction in elongation (∼32.0 %). The variation in Cr/Ni leads to the formation of a multi-scale heterogeneous structure, which induces the hetero-deformation induced strengthening effect, significantly enhancing the alloy's work hardening ability and ultimately achieving an excellent strength-ductility balance. This study systematically explores the composition-microstructure-mechanical property relationships, offering a pathway to engineer multiscale hierarchical microstructure in the Al-Cr-Fe-Ni system.

多主元素合金（mpea）为金属结构材料的发展提供了更广阔的成分和结构设计空间。在Al-Cr-Fe-Ni体系中，成分的细微变化可以诱导复杂的分层微观结构，从而有机会实现优异的强度-塑性协同作用。在这项工作中，一系列的Al14Fe20CrxNi66-x （x = 6,9,12,15 at）。采用Cr/Ni比调制和热处理相结合的方法设计并制备了mpea。随着Cr/Ni比的增大，催化裂化相由单一相向FCC/B2双相转变，B2相固定催化裂化相晶界，细化晶粒尺寸。同时，Cr/Ni比的增加改变了L12和BCC在纳米尺度上的体积分数和尺寸。获得的多尺度分层微观结构显著提高了室温强度，将抗拉强度从~ 905 MPa提高到~ 1233 MPa，延伸率略有降低（~ 32.0%）。Cr/Ni含量的变化导致合金形成多尺度非均相组织，从而诱发异质变形诱导强化效应，显著提高合金的加工硬化能力，最终达到良好的强度-塑性平衡。本研究系统地探索了成分-显微组织-力学性能之间的关系，为设计Al-Cr-Fe-Ni体系的多尺度分层微观结构提供了途径。

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引用次数: 0

Natural aging microstructure evolution mechanism in cryogenic pretreated high-alloy Al-Zn-Mg-Cu alloys 低温预处理高合金Al-Zn-Mg-Cu合金的自然时效组织演化机制

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-08 DOI: 10.1016/j.msea.2025.149597

Tao Wang , Haowen Cheng , Guoqing Zhao , Kenji Matsuda , Yong Zou

Solid-solution-treated 7055 Al-Zn-Mg-Cu alloy specimens were subjected to liquid nitrogen immersion (0–32 h durations) prior to natural aging, with mechanical properties (hardness/tensile strength) tested before and after natural aging. Electron backscatter diffraction (EBSD) quantified grain structure evolution, while transmission electron microscopy (TEM) identified natural aging precipitates. Comprehensive analysis revealed cluster nucleation predominantly occurred during cryogenic immersion, whereas dislocation proliferation/slip and grain boundary migration initiated during thermal recovery to ambient temperature. Vacancy-Mg binding preferentially promoted GP-I zone formation, facilitating subsequent η and T_NA phase precipitation, while extended cryogenic durations (>8 h) enhanced GP-II zone development leading to η′ phase nucleation. The classification of GP-I zone was first proposed according to the crystal structure as compact (GP-I_c), standard (GP-I_s), and expanded (GP-I_e) subtypes. The natural aging grain morphology can be affected by different recrystallization modes, namely, geometric recrystallization (GRX), continuous recrystallization (CRX), and discontinuous recrystallization (DRX), whose priority was subjected to the ability of dislocation proliferation/slip. Furthermore, dislocation-precipitate interactions also diversified the type and distribution of precipitates. These mechanistic insights provide foundational principles for designing cryogenically augmented heat treatments in high-alloy aluminum alloys.

固溶处理的7055 Al-Zn-Mg-Cu合金试样在自然时效前进行液氮浸泡（0-32 h），在自然时效前后测试力学性能（硬度/抗拉强度）。电子背散射衍射（EBSD）量化了晶粒结构演变，透射电镜（TEM）鉴定了自然时效析出物。综合分析表明，簇形核主要发生在低温浸渍过程中，而位错扩散/滑移和晶界迁移则发生在热恢复到环境温度的过程中。空位- mg结合优先促进GP-I区形成，促进后续η相和TNA相的析出，而延长低温时间（>8 h）促进GP-II区形成，导致η相成核。GP-I区根据晶体结构分为紧凑型（GP-Ic）、标准型（GP-Is）和扩展型（GP-Ie）三个亚型，首次被提出。自然时效晶粒形态受几何再结晶（GRX）、连续再结晶（CRX）和不连续再结晶（DRX）三种再结晶模式的影响，其优先性取决于位错扩散/滑移的能力。此外，位错-沉淀的相互作用也使沉淀的类型和分布多样化。这些机理见解为设计高合金铝合金的低温强化热处理提供了基本原理。

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引用次数: 0

Mechanisms of recrystallization and microstructure evolution during hot deformation of 550 MPa grade HSLA steel 550mpa级HSLA钢热变形再结晶机理及组织演变

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-08 DOI: 10.1016/j.msea.2025.149579

Shu-gang Cui , Pan-dong Lin , Wen-hua Xu , Guo-chao Gu , Chang-xin Shi , Yu-peng Lu

Understanding the hot deformation behavior of HSLA steel is essential for optimizing thermo-mechanical processing and controlling final microstructures. In this study, the dynamic recrystallization and microstructure evolution behaviors of 550 MPa grade high-strength low-alloy steel (HSLA) during thermal deformation were investigated using hot compression experiments and microstructure analysis. Tests were conducted at 900–1150 °C, with the strain rates of 0.01, 0.1, and 1 s⁻¹. The critical conditions for recrystallization were determined, and a corresponding kinetic model was established. The results show that the microstructure is dominated by martensite after hot deformation. When the deformation temperature was below 950 °C, a significant fraction of deformed austenite grains remained in the microstructure. Fine Nb (C, N) precipitates, with sizes of several nanometers, and Fe₃C carbides exhibiting a Bagaryatskii orientation relationship with the matrix were also observed. Based on the friction-corrected flow stress curve, the ratio of the recrystallization critical strain to the peak strain was found to be about 0.419. Meanwhile, the softening mechanism during hot deformation consists of the combined effect of mainly Discontinuous dynamic recrystallization and dynamic recovery.

了解高强度钢的热变形行为对优化热机械加工和控制最终组织具有重要意义。通过热压缩实验和显微组织分析，研究了550 MPa级高强度低合金钢（HSLA）在热变形过程中的动态再结晶和显微组织演变行为。试验在900-1150°C下进行，应变速率为0.01、0.1和1 s−1。确定了再结晶的临界条件，并建立了相应的动力学模型。结果表明：热变形后的组织以马氏体为主；当变形温度低于950℃时，组织中仍有大量形变的奥氏体晶粒残留。此外，还观察到细小的Nb （C， N）析出物（尺寸为几纳米）和Fe3C碳化物（与基体呈Bagaryatskii取向关系）。基于摩擦修正流动应力曲线，再结晶临界应变与峰值应变之比约为0.419。热变形过程中的软化机制主要是不连续动态再结晶和动态恢复的共同作用。

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引用次数: 0

Accelerated and enhanced artificial ageing of 2195 Al-Li alloy by electric current 电流加速和增强2195铝锂合金的人工时效

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-08 DOI: 10.1016/j.msea.2025.149589

Hongrui Dong , Xiaoqiang Li , Shiteng Zhao , Xiaochun Liu , Yanqin Wang , Yong Wu , Hang Yuan , Zhenxiao Wang , Yong Li

An accelerated artificial ageing process with the enhanced strength of 2195 Al-Li alloy has been reported and systematically characterized under the excitation of electric current in this study. Compared with conventional ageing (CA), electrically-assisted ageing (EAA) reduces the time to reach the equivalent peak strength by 42 %. More importantly, EAA achieves a significantly higher peak yield strength of 439 MPa, substantially exceeding the CA peak of 387 MPa. Through combined in-situ and ex-situ microstructural analyses, the accelerated precipitation kinetics and strength enhancement under EAA are attribute to the enhanced atom diffusion, nucleation and transformation kinetics of precipitates due to current-induced electro migration effect and drift electro scattering effects. Specifically, the more nucleation sites for θ′ phase at the early ageing stage and more fine T₁ phase at the late ageing stage result in higher yield strength under EAA. The results and methods presented here provide a potential way for the further design of fast ageing of Al-Li alloys with electric energy.

本文报道了2195铝锂合金在电流激励下的加速人工时效过程，并对其强度的提高进行了系统表征。与常规时效（CA）相比，电辅助时效（EAA）使材料达到等效峰值强度的时间缩短了42%。更重要的是，EAA的屈服强度峰值达到了439 MPa，大大超过了CA的387 MPa。结合原位和非原位的显微组织分析，发现EAA作用下析出物的加速析出动力学和强度增强是由于电流诱导的电迁移效应和漂移电散射效应增强了析出物的原子扩散、成核和转变动力学。其中，时效早期θ′相的形核位点越多，时效后期T1相的形核位点越细，在EAA作用下屈服强度越高。本文的研究结果和方法为进一步设计利用电能快速时效的铝锂合金提供了一条可能的途径。

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引用次数: 0

Multi-scale insights into Ti(C,N)-reinforced CoCr0.5FeNiTi0.2high-entropy alloys via in-situ synthesis microstructural evolution and strengthening mechanisms 原位合成Ti（C，N）增强cocr0.5 feniti0.2高熵合金显微组织演化及强化机制的多尺度研究

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-08 DOI: 10.1016/j.msea.2025.149587

Jidong Zhang, Yifan Guo, Haiwei Zhao, Hui-zhong Ma, Lan Zhang

A novel in-situ synthesis strategy employing graphitic carbon nitride (g-C₃N₄) as a dual C–N precursor was developed to fabricate Ti(C,N)/CoCr_0.5FeNiTi_0.2 composites. The controlled decomposition of g-C₃N₄ at 1050 °C enabled uniform Ti(C,N) precipitation with semi-coherent interfaces, leading to refined grains (∼2.1 μm), elevated dislocation density, and enhanced interfacial load transfer. At the optimum reinforcement level (1.0 wt% g-C₃N₄), the composite exhibited 99.3 % relative density, 857 HV hardness, and 1297 MPa ultimate tensile strength. Multi-scale characterization combined with molecular dynamics simulations revealed that Ti(C,N) particles enhance mechanical properties through grain refinement, dislocation hindrance, thermal-mismatch-induced residual stresses, and effective load transfer. At the atomic scale, Ti(C,N) acted simultaneously as dislocation sources and obstacles, markedly increasing dislocation density, while stacking-fault networks at subgrain boundaries further contributed to yield-strength increments. A quantitative strengthening model accurately predicted the experimental results with deviations below 5 %. The MD simulations reproduced the dynamic interfacial failure process, including atomic rearrangement, bond rupture, critical yielding, and ultimate fracture. The study delivers a high-performance HEA composite while elucidating processing–microstructure–property correlations, thereby advancing the understanding of strengthening mechanisms and providing the design of nanoparticle-reinforced metallic materials.

采用石墨化碳氮（g-C3N4）作为双碳氮前驱体制备Ti(C，N)/CoCr0.5FeNiTi0.2复合材料。在1050℃下g-C3N4的控制分解使Ti（C，N）在半共格界面均匀析出，导致晶粒细化（~ 2.1 μm），位错密度升高，界面载荷传递增强。在最佳增强水平（1.0 wt% g-C3N4）下，复合材料的相对密度为99.3%，硬度为857 HV，极限抗拉强度为1297 MPa。多尺度表征结合分子动力学模拟表明，Ti（C，N）颗粒通过晶粒细化、位错阻挡、热失配引起的残余应力和有效的载荷传递来提高力学性能。在原子尺度上，Ti（C，N）同时作为位错源和障碍，显著增加了位错密度，而亚晶界的堆积-断层网络进一步促进了屈服强度的增加。定量强化模型准确预测实验结果，误差小于5%。MD模拟再现了动态界面破坏过程，包括原子重排、键断裂、临界屈服和最终断裂。该研究提供了高性能HEA复合材料，同时阐明了加工-微观结构-性能的相关性，从而促进了对强化机制的理解，并为纳米颗粒增强金属材料的设计提供了依据。

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引用次数: 0

Achieving superior strength and ductility in NiCrCo-based medium entropy alloy via incorporating refractory W and Ta contents 通过添加耐火材料W和Ta，获得nicrco基中熵合金优异的强度和延展性

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-08 DOI: 10.1016/j.msea.2025.149590

Tao Huang , Kaiju Lu , Fengchun Jiang , Jingyuan Liu , Yanbo Zhang , Yang Zhou , Wengang Bu , Xiubing Liang

Single-phase face-centered cubic (FCC) medium-entropy alloys (MEAs) often possess excellent toughness but insufficient strength. To overcome this shortcoming, refractory W and Ta contents were incorporated into non-equiatomic NiCrCo MEA (Ni₅₉Cr₂₃Co₁₁W₅Ta₂, at. %). The designed alloy exhibits outstanding mechanical properties, with yield strength of 924 MPa and fracture strain of 40 % at 298 K, along with yield strength of 1.2 GPa and fracture strain of 47 % at 77 K. Theoretical calculations revealed that refractory W and Ta contents significantly promote lattice distortion, solid solution strengthening and grain boundary strengthening. Density functional theory (DFT) calculations further demonstrated that the Ni₅₉Cr₂₃Co₁₁W₅Ta₂ MEA exhibits a low intrinsic stable stacking fault energy (SFE) and a high unstable SFE. This enables a tunable deformation behavior from dislocation slip-dominated behavior at 298 K to twinning-assisted plasticity at 77 K, which contributed to concurrent improvements in strength and ductility at 77 K. Overall, this study paves a new path toward achieving a synergistic enhancement in strength and ductility through simultaneous regulation of atomic volume misfits and SFE via alloying with refractory contents.

单相面心立方（FCC）中熵合金通常具有良好的韧性，但强度不足。为了克服这一缺点，将难熔W和Ta含量掺入非等原子NiCrCo MEA （Ni59Cr23Co11W5Ta2, at）中。%)。所设计的合金具有优异的力学性能，在298 K时屈服强度为924 MPa，断裂应变为40%；在77 K时屈服强度为1.2 GPa，断裂应变为47%。理论计算表明，耐火材料中W和Ta的含量显著促进了晶格畸变、固溶强化和晶界强化。密度泛函理论（DFT）进一步表明，Ni59Cr23Co11W5Ta2 MEA具有较低的本征稳定层错能（SFE）和较高的不稳定层错能。这使得从298 K时的位错滑移主导行为到77 K时的孪晶辅助塑性的可调变形行为成为可能，这有助于同时提高77 K时的强度和延展性。总的来说，本研究为同时调节原子体积错配和耐火材料含量合金的SFE来实现强度和延性的协同增强铺平了新的道路。

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