Materials Characterization最新文献_第6页

Towards measuring absolute residual stress by HR-EBSD with simulated reference patterns 利用模拟参考模式通过 HR-EBSD 测量绝对残余应力

IF 4.8 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Materials Characterization

Pub Date : 2024-11-05 DOI: 10.1016/j.matchar.2024.114508

Qiwei Shi , Hongru Zhong , Dominique Loisnard , Matthew Nowell , Maxime Mollens , Zhe Chen , Haowei Wang , Stéphane Roux

The High-Resolution Electron Backscatter Diffraction (HR-EBSD) technique has drawn attention in recent years, mainly thanks to its ability to assess the elastic strain/stress state with a sub-micron spatial resolution. Each diffraction pattern is correlated with a reference one, and the strain level relative to the reference is retrieved in the procedure. Several studies have attempted to use dynamically simulated diffraction patterns as references to access absolute strain/stress states to circumvent the difficulty of finding a strain-free reference pattern, which is often inaccessible. Numerous factors need to be considered and corrected to register better experimental and simulated diffraction patterns, such as the accurate positioning of the projection center, Kikuchi band (K-band) brightness asymmetry, K-band gray level reversal, optical distortion, or non-uniform electron energy. Here, an integrated digital image correlation method is proposed to register experimental patterns to a master pattern defined on a sphere, where the difficulties with experimental patterns are, for the most part, corrected efficiently. Due to the shallow inspection depth of EBSD, the free-surface property (vanishing stress vector at the observation surface) is also adopted to reduce the degrees of freedom and enhance precision. Through several tests on high-quality experimental patterns, the proposed method proves robust and precise. Both the systematic and random errors of the residual strain results are several

10^{- 4}

. The method also allows the simultaneous determination of residual stress and the projection center coordinates.

高分辨率电子反向散射衍射（HR-EBSD）技术近年来备受关注，这主要归功于它能够以亚微米级的空间分辨率评估弹性应变/应力状态。每个衍射图样都与参考图样相关联，并在程序中检索相对于参考图样的应变水平。有几项研究尝试使用动态模拟衍射图样作为参考，以获取绝对应变/应力状态，从而避免了寻找无应变参考图案的困难，因为这种图案往往无法获得。为了更好地记录实验和模拟衍射图样，需要考虑和校正许多因素，如投影中心的精确定位、菊地波段（K 波段）亮度不对称、K 波段灰度反转、光学失真或电子能量不均匀等。这里提出了一种集成数字图像相关方法，用于将实验图案与球面上定义的主图案进行配准，在很大程度上有效地解决了实验图案的难题。由于 EBSD 的检测深度较浅，因此还采用了自由表面特性（观察表面的应力矢量消失）来减少自由度并提高精度。通过对高质量实验图案的多次测试，证明了所提出方法的稳健性和精确性。残余应变结果的系统误差和随机误差均为 10-4。该方法还能同时确定残余应力和投影中心坐标。

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引用次数: 0

High cycle fatigue properties of Ti-48Al-2Cr-2Nb alloy additively manufactured via twin-wire directed energy deposition-arc 通过双丝定向能沉积-电弧添加制造的 Ti-48Al-2Cr-2Nb 合金的高循环疲劳特性

IF 4.8 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Materials Characterization

Pub Date : 2024-11-05 DOI: 10.1016/j.matchar.2024.114526

Wenlu Zhou , Chen Shen , Lin Wang , Ting Zhang , Ying Li , Jianwen Xin , Yuelong Zhang , Fang Li , Yuhan Ding , Kanglong Wu , Danqi Zhang , Xueming Hua

Recently, additive manufacturing for titanium aluminide has received sustained attention. Considering the extensive applications on low pressure turbine blades in aerospace field, dynamic mechanical properties of titanium aluminide, especially the fatigue properties, are of great importance. In present work, fatigue test at ambient temperature was conducted for the first time on twin-wire directed energy deposition-arc (TW-DED-arc) fabricated Ti-48Al-2Cr-2Nb alloy with equiaxed lamellar colonies. More detailed researches on fatigue fracture characteristics and deformation modes are also investigated. The experiment results indicate that TW-DED-arc fabricated Ti-48Al-2Cr-2Nb alloy exhibits flat S–N behavior with a good resistance to fatigue. Fatigue life fluctuates widely at same stress level, but such fluctuations gradually weaken as stress decreases. Furthermore, γ/α₂ interface and lamellar colony boundary as well as special microstructures of as-fabricated Ti-48Al-2Cr-2Nb alloy are weak areas during fatigue process, which easily become crack nucleation sites. As stress level decreases, deformation mode of as-fabricated Ti-48Al-2Cr-2Nb alloy translates from twinning and dislocation slip to predominantly dislocation slip. In general, these findings provide an important reference for engineering applications of titanium aluminide.

最近，铝钛合金的增材制造技术受到了持续关注。考虑到低压涡轮叶片在航空航天领域的广泛应用，铝钛合金的动态机械性能，尤其是疲劳性能，显得尤为重要。在本研究中，首次对双丝定向能沉积电弧（TW-DED-arc）制造的具有等轴片状菌落的 Ti-48Al-2Cr-2Nb 合金进行了环境温度下的疲劳测试。此外，还对疲劳断裂特性和变形模式进行了更详细的研究。实验结果表明，TW-DED-电弧制造的 Ti-48Al-2Cr-2Nb 合金表现出平坦的 S-N 行为，具有良好的抗疲劳性。在相同应力水平下，疲劳寿命波动较大，但随着应力的减小，这种波动逐渐减弱。此外，Ti-48-Al-2Cr-2Nb 合金的 γ/α2 界面和片状集落边界以及特殊的微观结构是疲劳过程中的薄弱区域，容易成为裂纹成核点。随着应力水平的降低，成品 Ti-48Al-2Cr-2Nb 合金的变形模式从孪生和位错滑移转变为以位错滑移为主。总之，这些发现为铝化钛的工程应用提供了重要参考。

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引用次数: 0

Enhancing strength-ductility synergy in nano-sized TiB2/Al composite via rapid solidification and thermo-mechanical processing 通过快速凝固和热机械加工提高纳米级 TiB2/Al 复合材料的强度-电导率协同效应

IF 4.8 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Materials Characterization

Pub Date : 2024-11-05 DOI: 10.1016/j.matchar.2024.114529

Lei Wang , Zhe Chen , Sanqiang Yang , Haowei Wang

The Al-Cu-Mn (AA2219) composite reinforced by 5 wt% nano-sized TiB₂ particles were fabricated by hot isostatic pressing (HIP) combined with thermal-mechanical processing to achieve a superior strength-ductility combination. Coupling the comprehensive characterizations and microstructure-based analysis, the strength-ductility mechanisms were deeply understood. Results reveal that the uniform dispersed nano-sized TiB₂ particles under the current preparation process helps to improve the mechanical properties of the composite. The introduction of pre-stretch before artificial aging produced a fine θ' and S precipitates. By combining high-resolution TEM and crystal structure analysis, Al(Cu) and S phase at TiB₂/Al interface were identified, and their mismatch (δ) with Al were 3.8 % and 4.8 %, respectively. Mechanisms related to pre-stretch effects on the formation of dislocation, θ' and S precipitates and corresponding structures are discussed, as well as the implications of TiB₂/Al interface characteristics on strength and ductility.

通过热等静压（HIP）与热机械加工相结合的方法，制备了由 5 wt% 的纳米级 TiB2 颗粒增强的铝-铜-锰（AA2219）复合材料，实现了优异的强度-电导率组合。结合综合表征和基于微观结构的分析，深入了解了强度-电导机制。结果表明，当前制备工艺下均匀分散的纳米级 TiB2 颗粒有助于提高复合材料的力学性能。在人工老化前引入预拉伸，可产生细小的θ'和S析出物。通过结合高分辨率 TEM 和晶体结构分析，确定了 TiB2/Al 界面的 Al（Cu）相和 S 相，它们与 Al 的不匹配度（δ）分别为 3.8 % 和 4.8 %。讨论了预拉伸效应对位错、θ'和 S 沉淀及相应结构形成的相关机制，以及 TiB2/Al 界面特性对强度和延展性的影响。

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引用次数: 0

Novel Mo: CoFe2O4 nanoparticles combustion synthesis for opto-magneto-electrochemical applications: A systematic analysis 用于光磁电化学应用的新型 Mo: CoFe2O4 纳米粒子燃烧合成：系统分析

IF 4.8 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Materials Characterization

Pub Date : 2024-11-05 DOI: 10.1016/j.matchar.2024.114514

Njod Al Sdran , Kamlesh V. Chandekar , Sajid Ali Ansari , Mohd Shkir

In current work, various concentrations (0.0 wt%, 0.10 wt%, 0.25 wt%, 0.50 %,0.75 wt%, and 1 wt%) of Molybdenum (Mo) - doped cobalt ferrite (CFO) nanoparticles (Mo:CFO NPs) were synthesized using the flash combustion approach. The structural analysis of the prepared Mo:CFO was examined by the XRD patterns, and the obtained crystallite size 48.64, 46.72, 22.81, 21.05, 18.03, and 19.31 nm for 0.0 wt%, 0.10 wt%, 0.25 wt%, 0.50 wt%, 0.75 wt%, and 1 wt% Mo:CFO NPs, respectively. The presence of stoichiometry and homogeneity of the prepared Mo:CFO NPs was confirmed by the EDX analysis. The five phonon modes of the prepared Mo:CFO NPs were recorded by FT-Raman spectra, and the phonon modes were observed around 220, 312, 479, 624, and 685 cm⁻¹ that corresponded o T_2g(2), E_g, T_2g(1), A_1g(2), and A_1g(1) symmetries, respectively. The grain sizes of the pure CFO and Mo:CFO NPs were evaluated using the images of scanning electron microscopy (SEM) and obtained in the range of 39–61 nm, respectively. The presence of valence states Co (2p), Fe (2p), O (1 s), and Mo (3d) in the prepared 1 wt% Mo:CFO NPs were examined by XPS spectra. The particle sizes ∼26.4 nm and ∼ 16.7 nm were obtained for pure CFO and 1 wt% Mo:CFO NPs using lognormal function fitting. The emission peaks at 445 ± 3, 521 ± 3, and 620 ± 2 nm in the PL spectra were observed by PL spectroscopy. The decrease in saturation magnetization Ms. (70.80–66.54 emu/g) and reduced remanent magnetization Mr. (24.22–18.64 emu/g) of prepared Mo: CFO NPs was observed in the MH analysis by SQUID analysis. The electrochemical study of Mo: CFO NPs (0.0 %, 0.25 %, 0.50 %, and 1.0 %) was done in a three-electrode assembly cell. The capacitance of values 650.0 Fg⁻¹, 800.0 Fg^-1, and 810.0 Fg⁻¹ for pure CFO, 0.25 % Mo: CFO, and 0.50 % Mo: CFO were recorded in electrochemical analysis. The highest capacitance of 840.0 Fg⁻¹ was observed for the electrode with 1.0 % Mo: CFO NPs. It was analyzed that the increase in CFO electrodes enhances their performance, and therefore, it can be utilized for multifunctional devices.

本研究采用闪燃法合成了不同浓度（0.0 wt%、0.10 wt%、0.25 wt%、0.50 %、0.75 wt% 和 1 wt%）的钼（Mo）掺杂钴铁氧体（CFO）纳米粒子（Mo:CFO NPs）。通过 XRD 图谱对所制备的 Mo:CFO 进行了结构分析，0.0 wt%、0.10 wt%、0.25 wt%、0.50 wt%、0.75 wt% 和 1 wt% Mo:CFO NPs 的结晶尺寸分别为 48.64、46.72、22.81、21.05、18.03 和 19.31 nm。所制备的 Mo:CFO NPs 的化学计量和均一性已通过 EDX 分析得到证实。傅立叶变换拉曼光谱记录了制备的 Mo:CFO NPs 的五种声子模式，在 220、312、479、624 和 685 cm-1 附近观察到的声子模式分别对应于 T2g(2)、Eg、T2g(1)、A1g(2)和 A1g(1)对称性。利用扫描电子显微镜（SEM）图像评估了纯 CFO 和 Mo:CFO NPs 的晶粒尺寸，结果分别为 39-61 nm。通过 XPS 光谱检测了所制备的 1 wt% Mo:CFO NPs 中是否存在价态 Co (2p)、Fe (2p)、O (1 s) 和 Mo (3d)。利用对数正态函数拟合得到纯 CFO 和 1 wt% Mo:CFO NPs 的粒径分别为 ∼26.4 nm 和 ∼16.7 nm。聚光光谱仪观察到聚光光谱中 445 ± 3、521 ± 3 和 620 ± 2 nm 处的发射峰。通过 SQUID 分析，制备的 Mo: CFO NPs 的饱和磁化率 Ms.（70.80-66.54 emu/g）下降，剩磁率 Mr.（24.22-18.64 emu/g）降低。在三电极组装电池中对 Mo: CFO NPs（0.0%、0.25%、0.50% 和 1.0%）进行了电化学研究。在电化学分析中，纯 CFO、0.25 % Mo: CFO 和 0.50 % Mo: CFO 的电容值分别为 650.0 Fg-1、800.0 Fg-1 和 810.0 Fg-1。含有 1.0 % Mo: CFO NPs 的电极电容最高，达到 840.0 Fg-1。分析结果表明，增加 CFO 电极可提高其性能，因此可用于多功能设备。

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引用次数: 0

Creep-fatigue interactive behavior and damage mechanism of TP321 stainless steel under hybrid-controlled conditions 混合控制条件下 TP321 不锈钢的蠕变-疲劳交互行为和损伤机理

IF 4.8 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Materials Characterization

Pub Date : 2024-11-05 DOI: 10.1016/j.matchar.2024.114528

Chenwei Zhang , Shanghao Chen , Hongchang Wang , Fengping Zhong , Ling Li , Qiang Liu , Chong Zhen , Xujia Wang , Lijia Luo , Shiyi Bao

In this study, Hybrid-controlled creep-fatigue (HCCF) tests were conducted on TP321 austenitic stainless steel under a variety of test conditions. The effects of strain amplitude, holding time, holding stress and temperature on the creep-fatigue behavior of TP321 austenitic stainless steel were not only analyzed in detail but also revealed the creep-fatigue damage interactive mechanism. The results demonstrated that a rise in test temperature and load holding time markedly induced creep deformation, resulting in a notable reduction in failure life. Additionally, an increase in test temperature led to the cessation of the cyclic hardening phenomenon. Secondly, the analysis of fracture morphology and X-ray computed tomography (X-CT) scanning results demonstrated that the transgranular cracks expanded inwards and connected with the intergranular voids under creep-fatigue interaction, forming a mixed intergranular and transcrystalline fracture mode. The presence of large creep cavities impeded the propagation of fatigue cracks when creep damage was the dominant phenomenon. Subsequently, the damage evolution mechanism was elucidated through microstructural analysis, which revealed that the impact of the slip bands on the triangular grain boundaries and the precipitation of carbides facilitated the nucleation of voids and the internal formation of intergranular microcracks, thereby causing creep-fatigue damage interaction. Finally, the TP321 austenitic stainless steel creep-fatigue damage interactive mechanism diagram was proposed in conjunction with the fracture morphological characteristics and microstructure.

本研究在多种试验条件下对 TP321 奥氏体不锈钢进行了混合控制蠕变疲劳（HCCF）试验。不仅详细分析了应变振幅、保持时间、保持应力和温度对 TP321 奥氏体不锈钢蠕变疲劳行为的影响，还揭示了蠕变疲劳损伤的交互机制。结果表明，试验温度和负载保持时间的增加会明显诱发蠕变变形，导致失效寿命显著缩短。此外，试验温度升高会导致循环硬化现象停止。其次，断口形貌分析和 X 射线计算机断层扫描（X-CT）结果表明，在蠕变-疲劳相互作用下，跨晶裂纹向内扩展并与晶间空隙相连，形成晶间和跨晶混合断裂模式。当蠕变损伤成为主要现象时，大蠕变空洞的存在阻碍了疲劳裂纹的扩展。随后，通过微观结构分析阐明了损伤演变机制，发现滑移带对三角晶界的影响和碳化物的析出促进了空洞的成核和晶间微裂纹的内部形成，从而导致蠕变-疲劳损伤相互作用。最后，结合断口形貌特征和显微组织，提出了 TP321 奥氏体不锈钢蠕变-疲劳损伤相互作用机理图。

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引用次数: 0

Roles of Al/Ni ratio and solidification cooling rate in grain boundary engineering of AlxCrFeMnNi(2-x) high entropy alloy 铝/镍比和凝固冷却速度在 AlxCrFeMnNi(2-x) 高熵合金晶界工程中的作用

IF 4.8 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Materials Characterization

Pub Date : 2024-11-04 DOI: 10.1016/j.matchar.2024.114507

By T.X. Wang , Y.X. Wu , W.Q. Liu , C.Y. Xiong , H.T. Jiang

In this work, the roles of Al/Ni ratio and solidification cooling rate in grain size, dendrite morphology and grain boundary characteristic of the Al_xCrFeMnNi_(2-x) (x = 0.3, 0.7 and1.0) high-entropy alloys (HEAs) were investigated. The results show that the increasing of Al/Ni ratio results in a transition from single-phase FCC to dual-phase BCC + B2 along with the reverse precipitation behavior of BCC phase. While the phase composition is not affected by solidification cooling rate. With the increasing of Al/Ni ratio and solidification cooling rate, a significant columnar-to-equiaxed transition (CET) behavior can be observed. That is, grain refinement and transition from columnar dendrites to equiaxial and cellular dendrites. This is mainly attributed to the constitutional supercooling (CS) caused by the solute interaction effect of Al and Ni, and which can be evaluated by P and Q parameters. In addition, in-situ formation of serrated grain boundaries (SGBs) can be also observed in solidification microstructures, and with the increasing of Al/Ni ratio, the proportion of SGBs increases gradually. Whether the B2 precipitated phase is present or not, the formation mechanism of SGBs is mainly attributed to the lattice strain energy caused by the segregation of Al and Ni. The strategy simultaneously achieving grain refinement, CET and in-situ forming SGBs during solidification by tailoring Al/Ni ratio opens new perspectives for grain boundary engineering.

本文研究了铝/镍比和凝固冷却速度对 AlxCrFeMnNi（2-x）（x = 0.3、0.7 和 1.0）高熵合金（HEAs）的晶粒尺寸、枝晶形态和晶界特征的影响。结果表明，铝/镍比的增加导致单相 FCC 向 BCC + B2 双相过渡，同时 BCC 相出现反向沉淀行为。相组成不受凝固冷却速率的影响。随着铝/镍比和凝固冷却速率的增加，可以观察到明显的柱状向等轴状转变（CET）行为。也就是说，晶粒细化并从柱状枝晶过渡到等轴和蜂窝状枝晶。这主要归因于铝和镍的溶质相互作用效应引起的立宪过冷（CS），可通过 P 和 Q 参数进行评估。此外，在凝固微观结构中还可以观察到锯齿状晶界（SGBs）的原位形成，并且随着铝镍比的增加，SGBs 的比例也逐渐增加。无论是否存在 B2 沉淀相，锯齿状晶界的形成机理主要归因于铝和镍偏析引起的晶格应变能。通过调整铝镍比同时实现晶粒细化、CET和凝固过程中原位形成SGB的策略为晶界工程开辟了新的前景。

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引用次数: 0

Investigating the thermal-chemical-mechanical coupling effects on the cracking behavior of machine gun barrel: Microstructural insights 研究热-化学-机械耦合效应对机枪枪管开裂行为的影响：微观结构见解

IF 4.8 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Materials Characterization

Pub Date : 2024-11-04 DOI: 10.1016/j.matchar.2024.114522

Cheng Zhang , Yang Wang , Jun Xue , Junsong Li , Shujing Wang , Pengfei Jin , Xiaoshuai Shi , Cheng Zhang , Caihong Dou , Junyu Chen , Jinfeng Huang

The presence of severe cracks at the inner bore of the gun barrel accelerates the erosion failure, whereas the evolution and failure mechanism of crack tips under the thermal-chemical-mechanical coupling effects needs further investigation. Herein, the elemental distribution, phase structure, and strain surrounding the perpendicular and circumferential cracks in a failed gun barrel were investigated in detail by utilizing scanning electron microscopy (SEM), transmission Kikuchi diffraction (TKD), and transmission electron microscopy (TEM). Results indicated that the perpendicular crack was covered by double continuous layers composed of inner FeO oxides and outer Fe_0.96S sulfides. Notably, a high-density precipitation of FeO oxides together with severe lattice distortion and localized amorphization was observed at the crack tip, accelerating the growth of the cracks. For the circumferential crack, the presence of fine recrystallized grains alongside coarsened M₂₃C₆ carbides was observed at the crack tip. There was a high level of strain concentration along high-angle grain boundaries at the forefront of the circumferential crack tip, resulting in the cracking along grain boundaries. Furthermore, the models for propagation of perpendicular and circumferential cracks under the thermal-chemical-mechanical coupling effects were proposed respectively.

枪管内孔严重裂纹的存在加速了侵蚀失效，而裂纹尖端在热-化学-机械耦合效应下的演变和失效机理则有待进一步研究。本文利用扫描电子显微镜（SEM）、透射菊池衍射（TKD）和透射电子显微镜（TEM）详细研究了失效炮管中垂直和圆周裂纹周围的元素分布、相结构和应变。结果表明，垂直裂纹被由内层 FeO 氧化物和外层 Fe0.96S 硫化物组成的双连续层所覆盖。值得注意的是，在裂纹尖端观察到了高密度的氧化铁沉淀以及严重的晶格畸变和局部非晶化，这加速了裂纹的生长。对于圆周裂纹，在裂纹尖端观察到细小的再结晶晶粒和粗化的 M23C6 碳化物。在圆周裂纹尖端前沿的高角度晶界处存在高度应变集中，导致沿晶界开裂。此外，还分别提出了热-化学-机械耦合效应下垂直裂纹和圆周裂纹的扩展模型。

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引用次数: 0

Effect of cold rolling on microstructure and mechanical behavior of Fe35Ni35Cr20Mn10 high-entropy alloy 冷轧对 Fe35Ni35Cr20Mn10 高熵合金显微组织和力学性能的影响

IF 4.8 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Materials Characterization

Pub Date : 2024-11-03 DOI: 10.1016/j.matchar.2024.114503

Jun Zhou , Hengcheng Liao , Hongmei Chen , Di Feng , Weijun Zhu

The effects of cold rolling on the microstructure evolution and mechanical behavior of Fe35Ni35Cr20Mn10 high-entropy alloys were investigated. The microstructure was characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The mechanical properties were examined using a CMT5105 tensile tester. The prepared alloy exhibited excellent plastic deformation ability during continuous cold rolling, with a reduction rate greater than 95 %. Cold rolling resulted in extensive grain elongation, formation of deformation bands within the grains, and development of crystallographic textures. The evolution of the microstructure was accompanied by dislocation slip, deformation twins, and formation of shear bands during multipass rolling to a thickness strain of 95 % at room temperature. As the rolling reduction increased, the Brass{110}〈112〉 texture and 〈111〉//RD texture further enhanced. Cold rolling led to substantial strengthening of the prepared alloy; as the rolling reduction increased, both strength and hardness gradually increased. When the rolling reduction reached 95 %, its ultimate tensile strength approached 1116 MPa, which is 2.2 times that in the homogenized condition but at the expense of reduced ductility. After severe cold rolling, an increase in dislocation density occurred along with a microstructure consisting of twins and a network of shear bands formed which enhanced hardness, yield strength, and tensile strength.

研究了冷轧对 Fe35Ni35Cr20Mn10 高熵合金微观结构演变和力学行为的影响。通过扫描电子显微镜、透射电子显微镜和 X 射线衍射对微观结构进行了表征。使用 CMT5105 拉伸试验机检测了合金的机械性能。所制备的合金在连续冷轧过程中表现出优异的塑性变形能力，其变形率大于 95%。冷轧导致了广泛的晶粒伸长、晶粒内变形带的形成以及结晶纹理的发展。在室温下进行厚度应变为 95% 的多道次轧制时，微观结构的演变伴随着位错滑移、变形孪晶和剪切带的形成。随着轧制减量的增加，黄铜{110}〈112〉纹理和〈111〉//RD纹理进一步增强。冷轧使制备的合金得到大幅强化；随着轧制减量的增加，强度和硬度都逐渐提高。当轧制减薄率达到 95% 时，其极限抗拉强度接近 1116 兆帕，是均匀化条件下的 2.2 倍，但以延展性降低为代价。经过剧烈冷轧后，位错密度增加，同时形成了由孪晶和剪切带网络组成的微观结构，从而提高了硬度、屈服强度和抗拉强度。

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引用次数: 0

Enhancement of mechanical properties in Ti2AlNb/Ti60 brazed joints via Nb foam-induced in-situ formation of tough Ti4Nb phase 通过 Nb 泡沫诱导原位形成坚韧的 Ti4Nb 相提高 Ti2AlNb/Ti60 焊接接头的机械性能

IF 4.8 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Materials Characterization

Pub Date : 2024-11-03 DOI: 10.1016/j.matchar.2024.114513

Peng Wang , Heng Shao , Haiyan Chen , Hongbo Zhang , Xin Nai , Shuai Zhao , Pengcheng Wang , Xiaoguo Song , Achilles Vairis , Wenya Li

Brazing titanium alloys with TiZrCuNi filler typically leads to numerous eutectic structures and brittle intermetallic compounds, compromising the mechanical properties of joints, particularly their toughness. To mitigate this issue, this study employs Ni and Nb foams as interlayers to join Ti₂AlNb and Ti60 alloy. The results show that using Ni foam as the interlayer only forms 17.8 % β-Ti phase in the brazing seam. In contrast, Nb foam as the interlayer promotes the in-situ formation of 38.5 % Ti₄Nb phase within the brazing seam, effectively balancing the coefficient of thermal expansion difference and reducing residual thermal stresses. Comparative analysis reveals that the Ti₄Nb phase has superior plasticity and toughness compared to the β-Ti phase, allowing for substantial strain energy storage. The interface between β-Ti phase and Zr₂Cu phase exhibits significant lattice mismatch, resulting in an incoherent interface. Conversely, the Nb foam interlayer produces a semi-coherent interface between Ti₄Nb and Zr₂Cu phases, characterized by reduced lattice mismatch, which enhances the interfacial bonding strength of the brazed joint. The Ti₂AlNb/Ti60 joints, when brazed with Nb foam under consistent conditions, achieved a shear strength of 414.6 MPa, which is approximately 18 % superior to that of joints brazed using the Ti-36.5Zr-10Ni-15Cu-0.5Co-0.5Nb amorphous filler solely. Additionally, the shear stress-strain curves of the joints with Nb foam exhibit a more pronounced yield stage compared to those with only filler. This study introduces a novel approach for improving the toughness of brazed joints in practical applications using titanium-based fillers.

使用 TiZrCuNi 填料钎焊钛合金通常会产生大量共晶结构和脆性金属间化合物，从而影响接头的机械性能，尤其是韧性。为缓解这一问题，本研究采用镍和铌泡沫作为中间层，连接 Ti2AlNb 和 Ti60 合金。结果表明，使用镍泡沫作为中间膜只能在钎缝中形成 17.8% 的 β-钛相。相比之下，以 Nb 泡沫作为中间膜可促进钎缝中 38.5% Ti4Nb 相的原位形成，从而有效平衡热膨胀系数差并减少残余热应力。对比分析表明，与 β-Ti 相相比，Ti4Nb 相具有更高的塑性和韧性，可以储存大量应变能量。β-Ti 相与 Zr2Cu 相之间的界面表现出明显的晶格失配，导致界面不连贯。相反，泡沫铌夹层在 Ti4Nb 相和 Zr2Cu 相之间形成了半相干界面，晶格失配减少，从而提高了钎焊接头的界面结合强度。在一致的条件下用 Nb 泡沫钎焊时，Ti2AlNb/Ti60 接头的剪切强度达到 414.6 兆帕，比仅使用 Ti-36.5Zr-10Ni-15Cu-0.5Co-0.5Nb 非晶填料钎焊的接头高出约 18%。此外，与仅使用填料的接头相比，使用 Nb 泡沫的接头的剪切应力-应变曲线表现出更明显的屈服阶段。这项研究介绍了一种在实际应用中使用钛基填料提高钎焊接头韧性的新方法。

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引用次数: 0

Effect of wall thickness on the precipitation behavior, microstructure, electrical conductivity and mechanical properties of copper alloy prepared by electron beam powder bed fusion 壁厚对电子束粉末床熔融制备的铜合金的析出行为、微观结构、导电性和机械性能的影响

IF 4.8 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Materials Characterization

Pub Date : 2024-11-03 DOI: 10.1016/j.matchar.2024.114518

Yunzhe Li, Shifeng Liu, Yan Wang, Jianyong Wang, Liangliang Zhang, Wenpeng Jia, Yingkang Wei

Electron beam powder bed fusion (EB-PBF) is one of the most promising technologies for preparing thin-walled copper alloy, because copper alloy have a high energy absorption rate for electron beam, and high preheating temperature can reduce the solidification temperature gradient and reduce the deformation of thin-walled parts. At present, there are few reports on the systematic research work on the EB-PBF of thin-walled CuCrZr alloy parts, and it's impossible to effectively supervise the production of complex thin-walled CuCrZr alloy parts. This work aims to investigate the effect of thickness on the microstructure and mechanical properties of CuCrZr alloy produced by EB-PBF. As the wall thickness decreases from 5.0 mm to 0.3 mm, the grain sizes of the XY and YZ planes decreased from 20.4 μm and 43.1 μm to 14.5 μm and 21.5 μm respectively, and the texture intensity decreased from 16.04 and 23.57 to 7.62 and 10.99. The analysis showed that Cr₂O₃ nanoprecipitates were precipitated in situ in the sample, and their average size decreased from 65.8 nm to 21.6 nm. Due to the reduction in grain and nanoprecipitate size, the performance of thin-walled samples is significantly enhanced, with yield strength (YS) increasing from 112 MPa to 165 MPa and conductivity increasing from 71.7 %IACS to 86.1 %IACS. Finally, the main contributions to the YS of specimens with different wall thicknesses was discussed. Precipitation strengthening and dislocation strengthening are the main strengthening mechanisms in thin-walled samples, and the gradual refinement of nano-precipitates is the main reason for the improvement of mechanical properties as the wall thickness decreases.

电子束粉末床熔化（EB-PBF）是制备薄壁铜合金最有前途的技术之一，因为铜合金对电子束的能量吸收率高，高预热温度可以降低凝固温度梯度，减少薄壁零件的变形。目前，关于薄壁 CuCrZr 合金零件 EB-PBF 的系统研究工作报道较少，无法有效监督复杂薄壁 CuCrZr 合金零件的生产。本研究旨在探讨厚度对 EB-PBF 生产的 CuCrZr 合金微观结构和机械性能的影响。随着壁厚从 5.0 mm 减小到 0.3 mm，XY 和 YZ 平面的晶粒大小分别从 20.4 μm 和 43.1 μm 减小到 14.5 μm 和 21.5 μm，纹理强度从 16.04 和 23.57 减小到 7.62 和 10.99。分析表明，样品中原位析出了 Cr2O3 纳米沉淀物，其平均粒度从 65.8 nm 减小到 21.6 nm。由于晶粒和纳米沉淀物尺寸的减小，薄壁样品的性能显著提高，屈服强度（YS）从 112 兆帕提高到 165 兆帕，导电率从 71.7 %IACS 提高到 86.1 %IACS。最后，讨论了不同壁厚试样对 YS 的主要贡献。沉淀强化和位错强化是薄壁试样的主要强化机制，而纳米沉淀物的逐渐细化是随着壁厚减小而提高机械性能的主要原因。

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引用次数: 0