Acta Materialia最新文献_第3页

A novel age-hardenable austenitic stainless steel with superb printability 一种新型时效硬化奥氏体不锈钢，具有极佳的可印刷性

IF 8.3 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2024-11-09 DOI: 10.1016/j.actamat.2024.120547

Huayan Hu , Tianji Zhao , Zehao Ning , Jian-Feng Wen , Tongde Shen , Shujuan Wang , Miao Song

Precipitation-hardened high strength alloys, such as nickel-based alloys, aluminum alloys and stainless steels, are susceptible to hot cracking during 3D printing. This issue is typically mitigated by reducing solute segregation or promoting columnar-to-equiaxed transition. Here, we demonstrate an alternative approach by increasing segregation solutes, especially Ti element, to reduce hot cracking during laser powder bed fusion (LPBF) additive manufacturing of a new austenitic stainless steel (ASS). Enhanced segregation triggers peritectic-like reactions at cell/grain boundaries, forming multiple phases that bridge FCC dendrites. As a result, the new ASS exhibited excellent printability across a broad range of processing parameters. The as-built (AB) steel displayed a heterogeneous columnar grain microstructure with fine L2₁/BCC/C14 precipitates partially decorating cell structures, achieving a yield strength (σ_0.2) above 690 MPa and uniform elongation (ε_u) beyond 17.5 %. The epitaxial growth of the columnar grains was frequently interrupted by puddles of fine grains, leading to near-isotropic tensile properties. Following isochronal annealing at temperatures between 600 and 1150 °C for two hours, the AB steel underwent varying degrees of microstructure evolution, resulting in a broad range of mechanical properties (σ_0.2 from 300 to 1460 MPa and ε_u from 59.5 % to 7.6 %). This high strength is attributed to the formation of the L2₁/σ/η multiple phases at cell and grain boundaries, in combination with coherent L1₂-ordered (γ') nanoparticles precipitated within cell interiors during aging. This study explored that compositional design leveraging the unique solidification behavior of the LPBF process can produce hierarchical-structured stainless steels with excellent printability and tunable mechanical performance.

沉淀硬化的高强度合金（如镍基合金、铝合金和不锈钢）在 3D 打印过程中容易出现热裂纹。这一问题通常通过减少溶质偏析或促进柱状向等轴状转变来缓解。在此，我们展示了另一种方法，即通过增加偏析溶质（尤其是钛元素）来减少新型奥氏体不锈钢（ASS）激光粉末床熔融（L-PBF）增材制造过程中的热裂纹。强化偏析会在晶胞/晶粒边界引发类似包晶的反应，形成桥接 FCC 树枝状的多相。因此，新型 ASS 在广泛的加工参数范围内都表现出优异的可印刷性。坯钢（AB）显示出异质柱状晶粒微观结构，细小的 L21/BCC/C14 沉淀部分装饰了晶胞结构，屈服强度（σ0.2）超过 690 兆帕，均匀伸长率（εu）超过 17.5%。柱状晶粒的外延生长经常被细小晶粒的水坑打断，从而导致近乎各向同性的拉伸特性。在 600 至 1150 °C 之间的温度下进行两小时等速退火后，AB 钢经历了不同程度的微观结构演变，从而获得了广泛的机械性能（σ0.2 从 300 到 1460 MPa，εu 从 59.5% 到 7.6%）。这种高强度归因于晶胞和晶粒边界形成的 L21/σ/η 多相，以及老化过程中晶胞内部析出的相干 L12 有序 (γ')纳米颗粒。本研究探讨了利用 L-PBF 工艺独特的凝固行为进行成分设计，可生产出具有出色的可印刷性和可调机械性能的分层结构不锈钢。

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引用次数: 0

A multi-scale modeling framework for solidification cracking during welding 焊接过程中凝固裂纹的多尺度建模框架

IF 8.3 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2024-11-08 DOI: 10.1016/j.actamat.2024.120530

Xiaohui Liang , Gautam Agarwal , Marcel Hermans , Cornelis Bos , Ian Richardson

A multi-scale multi-physics modeling framework has been developed to predict solidification cracking susceptibility (SCS) during welding. The framework integrates a thermo-mechanical finite element model to simulate temperature and strain rate profiles during welding, a cellular automata model to simulate the solidified microstructure in the weld pool, and a granular model to calculate the pressure drop in the mushy zone. Verification was achieved by comparing the model’s predictions with welding experiments on two steels, demonstrating its capability to accurately capture the effects of process parameters, grain refinement, and alloy composition on SCS. Results indicate that increasing welding velocity, while maintaining a constant power-to-velocity ratio, extends the size of the mushy zone and increases the maximum pressure drop in the mushy zone, leading to higher SCS. Grain refinement decreases separation velocities and the permeability of liquid channels, which increases SCS, but it also raises the coalescence temperature, resulting in an overall reduction in SCS. Alloy composition impacts SCS through thermal diffusivity and segregation. Lower thermal diffusivity or stronger segregation tends to elongate the mushy zone, resulting in an increase in SCS. This framework provides a robust tool for understanding the mechanisms of solidification cracking, optimizing welding parameters to prevent its occurrence, and comparing SCS of different compositions during alloy design.

为预测焊接过程中的凝固裂纹敏感性（SCS），开发了一种多尺度多物理模型框架。该框架集成了一个热机械有限元模型，用于模拟焊接过程中的温度和应变率曲线；一个单元自动机模型，用于模拟焊接熔池中的凝固微观结构；以及一个颗粒模型，用于计算粘稠区的压降。通过比较该模型的预测结果和两种钢材的焊接实验，验证了该模型能够准确捕捉工艺参数、晶粒细化和合金成分对 SCS 的影响。结果表明，在保持功率-速度比不变的情况下，提高焊接速度会扩大粘合区的大小，增加粘合区的最大压降，从而导致更高的 SCS。晶粒细化会降低分离速度和液体通道的渗透性，从而提高 SCS，但同时也会提高凝聚温度，导致 SCS 整体下降。合金成分通过热扩散和偏析影响 SCS。较低的热扩散率或较强的偏析往往会拉长粘稠区，从而导致 SCS 增加。这一框架为了解凝固裂纹的机理、优化焊接参数以防止其发生以及在合金设计过程中比较不同成分的 SCS 提供了强有力的工具。

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引用次数: 0

Hierarchical micro-nanostructured Zr-based metallic glass with tensile plasticity 具有拉伸可塑性的分层微纳米结构 Zr 基金属玻璃

IF 8.3 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2024-11-08 DOI: 10.1016/j.actamat.2024.120553

Dongpeng Wang , Mengwei Du , Yingchun Lin , Zhenzhen Dong , Hongti Zhang , Yicheng Wu , Xin Li , Yuxin Wang , Chain Tsuan Liu

Metallic glasses (MGs) exhibit many unique properties because of their disordered microstructure. However, the absence of tensile plasticity at room temperature severely restricts the potential of MGs as high-performance structural materials. Here, Zr-based MG with a hierarchically heterogeneous structure in length was fabricated to enhance the tensile plasticity. Higher structural heterogeneity with a characteristic length of 12–20 nm was obtained by thermal cycling treatment. Subsequently, a micron array with a lower elastic modulus was prepared via high-frequency vibration. The hierarchical micro-nanostructured Zr-based MG exhibits a tensile plasticity of 0.68% at room temperature. Combined with finite element calculations and molecular dynamics simulations, the mechanism of the plastic deformation is attributed to more activated deformation units at the nanoscale and shear bands blocking and branching by complicated stress distributions at the micrometer scale. The findings presented herein can expand the understanding of structural heterogeneity, and provide a theoretical foundation for enhancing the tensile plasticity of MGs.

金属玻璃（MGs）因其无序的微观结构而表现出许多独特的性能。然而，室温下没有拉伸塑性严重限制了金属玻璃作为高性能结构材料的潜力。为了提高拉伸塑性，本文制备了长度上具有分层异质结构的锆基 MG。通过热循环处理，获得了特征长度为 12-20 纳米的更高结构异质性。随后，通过高频振动制备了弹性模量较低的微米阵列。分层微纳米结构锆基 MG 在室温下的拉伸塑性为 0.68%。结合有限元计算和分子动力学模拟，塑性变形的机理可归结为纳米尺度上更多的活化变形单元以及微米尺度上复杂应力分布造成的剪切带阻塞和分支。本文的研究结果可以拓展对结构异质性的理解，并为增强 MGs 的拉伸塑性提供理论基础。

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引用次数: 0

Functional recycling of grain boundary diffusion processed Nd-Fe-B sintered magnets 晶界扩散加工钕铁硼烧结磁体的功能再循环

IF 8.3 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2024-11-08 DOI: 10.1016/j.actamat.2024.120532

Mario Schönfeldt , Jürgen Rossa , Konrad Opelt , Kilian Schäfer , Lukas Schäfer , Fernando Maccari , Matic Jovičević-Klug , Tim M. Schwarz , Chi-Chia Lin , Mahmudul Hasan , Jürgen Gassmann , Dierk Raabe , Oliver Gutfleisch

Sintered Nd-Fe-B magnets industrially produced employing the grain boundary diffusion process (GBD) were recycled by the so-called functional or short-loop recycling approach, based on hydrogen decrepitation (HD). Microstructural and magnetic differences between the original and the recycled materials were analyzed. The functional recycling of GBD magnets leads to the dissolution of the core (heavy rare earth lean) - shell (heavy rare earth rich) structure through the different heat treatment steps which include hydrogen decrepitation, sintering, and annealing. The recycled magnets show similar rectangular demagnetization curves with squareness of 96 %, and only a slightly decreased remanence of 5 % to 1.31 T, but a larger decrease in coercivity of 21 % to 1703 kA/m. A new GBD step using 1.5 wt.% Tb with a pure Tb-foil as diffusion source leads again to the formation of a core-shell structure with 0.5 µm thick Tb-shells which is similar to the microstructure of the original magnets prior to recycling. The coercivity of the recycled magnets is increased by 35 % from 1315 kA/m to 1780 kA/m at 50 °C and shows similar magnetic values as the original industrial magnets at 150 °C and 200 °C, respectively. The temperature coefficients for the remanence, α, and for the coercivity, β, can also be fully restored and even exceed the original values which leads to an improved temperature stability of the recycled magnets compared to the original magnets.

烧结钕铁硼磁体是利用晶界扩散工艺（GBD）通过所谓的功能或短环回收方法（基于氢气降解（HD））进行回收的。分析了原始材料和回收材料之间的微观结构和磁性差异。GBD 磁体的功能性再循环通过不同的热处理步骤（包括氢气降解、烧结和退火）导致磁芯（贫重稀土）-磁壳（富重稀土）结构的溶解。再循环磁体显示出相似的矩形退磁曲线，方正度为 96%，剩磁率仅略微下降 5%至 1.31 T，但矫顽力却大幅下降 21%至 1703 kA/m。新的 GBD 步骤使用 1.5 wt.% 的铽和纯铽箔作为扩散源，再次形成了 0.5 µm 厚铽壳的核壳结构，这与回收前原始磁体的微观结构相似。回收磁体的矫顽力在 50 °C 时增加了 35%，从 1315 kA/m 增加到 1780 kA/m，并分别在 150 °C 和 200 °C 时显示出与原始工业磁体相似的磁性值。剩磁温度系数 α 和矫顽力温度系数 β 也可以完全恢复，甚至超过原始值，这使得再生磁体的温度稳定性比原始磁体更好。

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引用次数: 0

Enhanced mechanical hardness of mixed-phase BiFeO3 films through quenching 通过淬火提高混合相 BiFeO3 薄膜的机械硬度

IF 8.3 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2024-11-07 DOI: 10.1016/j.actamat.2024.120539

Xueli Hu , Shuo Yan , Xiaomei Lu , Fengzhen Huang , Shuyu Xiao

Due to epitaxial strain, BiFeO₃ (BFO) thin films exhibit a morphotropic phase boundary with coexisting rhombohedral-like (R-like) and tetragonal-like (T-like) phases. The T-like phase, distinguished by its large c/a ratio and giant polarization, has garnered extensive interest. In this work, by quenching an epitaxial mixed-phase BFO thin film grown on a LaAlO₃ substrate, a pronounced transition from the R-like to the T-like phase is observed. This transition is concomitant with improved phase structure stability under the force field induced by an atomic force microscope tip. PeakForce Quantitative NanoMechanics mapping reveals that the T-like phase exhibits a higher Young's modulus than the R-like phase, signifying an overall enhancement in the mechanical hardness of the BFO film. This work introduces a simple but powerful approach to manipulating the fraction of the T-like phase in the mixed-phase BFO films, presenting prospects for enhancing their performance and expanding their application range in advanced techniques.

由于外延应变，BiFeO3（BFO）薄膜呈现出形态各向同性的相界，斜方体（R-like）相和四方体（T-like）相共存。类 T 相具有较大的 c/a 比和巨大的极化，因此引起了广泛的关注。在这项研究中，通过淬火在 LaAlO3 基底上生长的外延混合相 BFO 薄膜，观察到了从 R 相到 T 相的明显转变。在原子力显微镜尖端诱导的力场作用下，这种转变与相结构稳定性的提高同时发生。PeakForce 定量纳米力学绘图显示，T 型相比 R 型相具有更高的杨氏模量，这表明 BFO 薄膜的机械硬度得到了全面提高。这项工作介绍了一种简单但功能强大的方法来操纵混合相 BFO 薄膜中 T 样相的比例，为提高其性能和扩大其在先进技术中的应用范围提供了前景。

引用次数: 0

Densely packed glass structure caused by seven-coordinated Zr in high elastic modulus Al2O3–SiO2–ZrO2 glasses 高弹性模量 Al2O3-SiO2-ZrO2 玻璃中七配位 Zr 造成的致密玻璃结构

IF 8.3 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2024-11-06 DOI: 10.1016/j.actamat.2024.120549

Atsunobu Masuno , Yuki Mikami , Yutaka Yanaba , Yuji Higo , Shunta Sasaki , Io Sato , Toyonari Yaji , Gustavo A. Rosales-Sosa , Hiroyuki Inoue

Al₂O₃–SiO₂–ZrO₂ ternary glasses were fabricated using a levitation technique. The addition of ZrO₂ to the Al₂O₃–SiO₂ glasses strongly affected their thermal, mechanical, and structural properties. Several compositions were partially vitrified at the laser-melted area without levitation although their melting required temperatures higher than 2000 °C. With increasing ZrO₂ content, the elastic moduli linearly increased, and the 50Al₂O₃–20SiO₂–30ZrO₂ glass exhibited a Young′s modulus of 166 GPa and Vickers hardness H_V of 10.6 GPa. Conversely, crack resistance significantly decreased with the addition of ZrO₂. Density measurements, Zr L_2,3-edge and K-edge X-ray absorption fine structure analyses, and ²⁷Al and ²⁹Si magic-angle spinning nuclear magnetic resonance spectroscopy were performed to investigate the local structure around Zr, Al, and Si in the glasses. Zr formed distorted ZrO₇ as in monoclinic ZrO₂, which has been rarely found in conventional oxide glasses. The highly oxygen-coordinated Al atoms such as AlO₅ and AlO₆, were the main components in the glasses rather than AlO₄. The majority of Si atoms form SiO₄ with four bridging oxygen (Q⁴). Among the four bridging oxygens, the number of oxygens connected to Al or Zr clearly increased with decreasing SiO₂ content. The high packing density of the ternary glasses that resulted in high elastic moduli originated from the highly oxygen-coordinated Zr and Al and their close bonding with SiO₄ without generating nonbridging oxygens.

利用悬浮技术制造了 Al2O3-SiO2-ZrO2 三元玻璃。在 Al2O3-SiO2 玻璃中添加 ZrO2 对其热性能、机械性能和结构性能有很大影响。尽管熔化所需的温度高于 2000°C，但有几种成分在激光熔化区域部分玻璃化，而无需悬浮。随着 ZrO2 含量的增加，弹性模量呈线性增长，50Al2O3-20SiO2-30ZrO2 玻璃的杨氏模量为 166 GPa，维氏硬度 HV 为 11 GPa。相反，抗裂性随着 ZrO2 的添加而明显下降。为了研究玻璃中围绕 Zr、Al 和 Si 的局部结构，我们进行了密度测定、Zr L2,3-edge 和 K-edge X 射线吸收精细结构分析，以及 27Al 和 29Si 魔角旋转核磁共振波谱分析。锆在单斜 ZrO2 中形成了扭曲的 ZrO7，这在传统的氧化物玻璃中很少见。玻璃中的主要成分是高度氧配位的铝原子，如 AlO5 和 AlO6，而不是 AlO4。大部分硅原子与四个桥接氧（Q4）形成 SiO4。在四个桥接氧中，与 Al 或 Zr 连接的氧的数量明显随着二氧化硅含量的降低而增加。三元玻璃的高堆积密度导致了高弹性模量，这源于高度氧配位的 Zr 和 Al 以及它们与 SiO4 的紧密结合，而不会产生非桥氧。

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引用次数: 0

Achieving low thermal conductivity and high quality factor in sextuple-doped TiS2 实现六重掺杂 TiS2 的低导热性和高品质因数

IF 8.3 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2024-11-06 DOI: 10.1016/j.actamat.2024.120548

Jinxue Ding , Wei Li , Moritz Thiem , Konstantin P. Skokov , Nina Kintop , Anke Weidenkaff , Wenjie Xie

Transition-metal dichalcogenide TiS₂ stands out as a sustainable candidate for room- and medium-temperature thermoelectric materials due to its affordability, non-toxicity, eco-friendly nature and use of non-critical elements. However, its light element compositional nature results in a large thermal conductivity, which is the main limitation of the thermoelectric performance of TiS₂. Here, we report a multi-element doping strategy by incorporating equivalent (Se, Zr) elements and introducing higher-valence (Nb, Ta) and lower-valence (Y, La) elements in pairs to minimize its lattice thermal conductivity,

κ_{lat}

. The findings indicate a nearly 50 % decrease in

κ_{lat}

across the entire temperature range, attributed to the presence of strong point-defect scattering after multi-element doping. Additionally, we observed a reduced dependency of

κ_{lat}

on temperature in multi-element doped TiS₂, as point defects can effectively scatter phonons at room temperature. As a result, the multi-element doped TiS₂ attained its highest ZT value of approximately 0.4 at 625 K. Incorporating higher-valence and lower-valence elements in pairs proves to be an effective method for decreasing lattice thermal conductivity without compromising too much of its large Seebeck coefficient.

过渡金属二钴化物 TiS2 因其价格低廉、无毒、环保和使用非关键元素而成为室温和中温热电材料的可持续候选材料。然而，TiS2 的轻元素组成特性导致其热导率较大，这是限制其热电性能的主要因素。在此，我们报告了一种多元素掺杂策略，即掺入等价（Se、Zr）元素，并成对引入高价（Nb、Ta）和低价（Y、La）元素，以最大限度地降低其晶格热导率κlatκlat。研究结果表明，在整个温度范围内，κlatκlat 下降了近 50%，这归因于多元素掺杂后出现了强烈的点缺陷散射。此外，我们还观察到在多元素掺杂的 TiS2 中，κlatκlat 对温度的依赖性降低，因为点缺陷在室温下可以有效地散射声子。因此，多元素掺杂 TiS2 在 625 K 时达到了约 0.4 的最高 ZT 值。将高价元素和低价元素成对掺杂在一起，证明是降低晶格热导率的有效方法，而不会过多地影响其大塞贝克系数。

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引用次数: 0

Thermal conductivity of WC: Microstructural design driven by first-principles simulations 碳化钨的导热性：第一原理模拟驱动的微结构设计

IF 8.3 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2024-11-05 DOI: 10.1016/j.actamat.2024.120517

Samuel A. Humphry-Baker , Thomas A. Mellan , Mike Finnis , Peter Polcik , William E. Lee , Mike Reece , Salvatore Grasso

The relationships between the microstructure and the thermal conductivity of binderless WC have been quantified, considering crystal orientation, isotopic abundance, porosity, and grain size. A significantly higher conductivity is predicted in the out-of-plane (c-axis) direction vs. the in-plane (a-axis) direction, using first principles simulations. Isotopic enrichment of the tungsten sublattice is predicted to increase conductivity, e.g., by a factor of 4–5 in the absence of boundary scattering. The results suggest that for an isotopically pure single crystal a thermal conductivity exceeding 1000 W m⁻¹ K⁻¹ may be achievable normal to the basal plane. The conductivity of samples with various porosities could be well fit by a minimum surface area (exponential) model, with a porosity exponent of b = 4.4. Experiment and simulation show a strong grain size dependence to conductivity below 1 µm, with a saturation beyond ∼10 µm. The experimental plateau values for κ were ∼45 % lower than those of the simulations due to deviations from perfect stoichiometry. We also find a higher scattering coefficient in the experiments, likely due to effects of grain size distribution and elongation. Our study clarifies the physical origin of disagreeing literature reports as being predominantly due to grain boundary scattering and enables microstructural design for thermally demanding environments.

考虑到晶体取向、同位素丰度、孔隙率和晶粒尺寸，我们对无粘结剂碳化钨的微观结构与热导率之间的关系进行了量化。根据第一原理模拟预测，面外（c 轴）方向的热导率明显高于面内（a 轴）方向。据预测，钨亚晶格的同位素富集会提高导电率，例如，在没有边界散射的情况下，导电率会提高 4-5 倍。结果表明，对于同位素纯净的单晶体，其热导率可超过 1000 W m-1 K-1。各种孔隙率样品的导热率都可以用最小表面积（指数）模型很好地拟合，孔隙率指数为 b = 4.4。实验和模拟结果表明，1 微米以下的电导率与晶粒大小密切相关，超过 10 微米后达到饱和。由于偏离了完美的化学计量，κ 的实验高原值比模拟值低 45%。我们还发现实验中的散射系数更高，这可能是由于晶粒尺寸分布和伸长率的影响。我们的研究澄清了文献报告中存在分歧的主要原因是晶界散射的物理来源，并使微结构设计能够适应热要求较高的环境。

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引用次数: 0

Constructing high-performance bulk thermoelectric composites by incorporating uniformly dispersed fullerene sub-nanoclusters 通过加入均匀分散的富勒烯亚纳米团簇构建高性能块状热电复合材料

IF 8.3 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2024-11-05 DOI: 10.1016/j.actamat.2024.120540

Fanshi Wu , Yifan Shi , Wanjia Zhang , Wei Zhao , Hao Yang , Wenxin Lai , Yue Lou , Zhenhua Yan , Zhan Shi , Zhenhua Ge , Xiyang Wang , Liangwei Fu , Biao Xu

Sub-nanomaterials possess unprecedented size-dependent properties compared to conventional nanomaterials, which endow them with great potential in catalysis, biomedicine, sensors, and so on. However, their applications in thermoelectrics are unknown due to poor thermal stability and low yields. Herein, we construct a series of thermoelectric composites by incorporating highly thermally stable and commercial fullerene sub-nanoclusters (C₆₀ or C₇₀). We find that sub-nanoclusters as the second phase can conduce to optimized carrier concentration through charge transfer at interfaces while the carrier mobility is significantly enhanced due to atom orbital hybridization and size-dependent electrical scattering mechanism. Furthermore, the ultra-low thermal conductivity of C₆₀ due to its distorted chemical bonding and sub-nanometer pore, and the interfacial thermal resistance greatly suppress the phonon transport. Consequently, the 0.15 mol.% C₆₀/Bi_0.4Sb_1.6Te₃ realizes an ultra-high ZT of ∼1.6 at 373 K, an excellent thermoelectric conversion efficiency of ∼7.4 %, and a huge cooling performance of ∼73 K. This work demonstrates the application of sub-nanomaterials in thermoelectrics and may shed light on other fields such as electronic devices, thermal management, and fullerene chemistry.

与传统纳米材料相比，亚纳米材料具有前所未有的尺寸特性，这赋予了它们在催化、生物医学、传感器等领域的巨大潜力。然而，由于热稳定性差和产量低，它们在热电领域的应用尚不为人知。在本文中，我们通过加入高热稳定性的商用富勒烯亚纳米团簇（C60 或 C70），构建了一系列热电复合材料。我们发现，亚纳米团簇作为第二相，可通过界面上的电荷转移优化载流子浓度，同时由于原子轨道杂化和尺寸依赖性电散射机制，载流子迁移率显著提高。此外，C60 因其扭曲的化学键和亚纳米孔隙而具有超低的热导率，而界面热阻则极大地抑制了声子传输。因此，0.15 mol% C60/Bi0.4Sb1.6Te3 在 373 K 时实现了 ∼1.6 的超高 ZT、∼7.4% 的优异热电转换效率和∼73 K 的巨大冷却性能。这项工作展示了亚纳米材料在热电领域的应用，并可能为电子器件、热管理和富勒烯化学等其他领域带来启示。

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引用次数: 0

Enhancing thermal stability of Nb nanowires in a NiTiFe matrix via texture engineering 通过纹理工程提高镍钛铁基体中铌纳米线的热稳定性

IF 8.3 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Acta Materialia

Pub Date : 2024-11-04 DOI: 10.1016/j.actamat.2024.120525

Yuxuan Chen , Yang Li , Suoqing Yu , Junsong Zhang , Shan Huang , Feihong Chu , Xiaobin Shi , Kaixuan Li , Zishu Lian , Daqiang Jiang , Yang Ren , Lishan Cui , Kaiyuan Yu

Metallic nanowires, renowned for their high strength and large elastic strain limits, have shown significant potential in rendering extraordinary structural and functional properties in composites. However, their integrity at high temperatures is often compromised due to fragmentation and spheroidization, processes driven by excess interfacial energy. Here, we demonstrate in a NiTiFe/Nb nanocomposite that the fragmentation and spheroidization of Nb nanowires can be significantly suppressed by tailoring the interfacial crystallographic orientation relationship between the nanowires and the matrix. By doping Fe into NiTi, we inhibit the typical deformation-induced amorphization of the NiTi-based matrix during severe deformation processing. The common (111)_NiTi//(110)_Nb texture is inherently suppressed and (110)_NiTiFe//(110)_Nb texture is formed instead. Such a change in texture allows Nb nanowires to retain their integrity up to 700 °C in the NiTiFe matrix, in contrast to the 550 °C in the counterparts. Simulation results indicate that the enhanced thermal stability of Nb nanowires is attributed to the reduced interfacial energy between (110)_NiTiFe and (110)_Nb. Additionally, Fe doping elevates the migration energy barrier for Nb diffusion, imposing further resistance to fragmentation and spheroidization.

金属纳米线以其高强度和大弹性应变极限而著称，在复合材料中提供非凡的结构和功能特性方面显示出巨大的潜力。然而，由于碎裂和球化（由过剩的界面能量驱动的过程），它们在高温下的完整性往往受到损害。在这里，我们在 NiTiFe/Nb 纳米复合材料中证明，通过调整纳米线和基体之间的界面晶体取向关系，可以显著抑制 Nb 纳米线的碎裂和球化。通过在镍钛中掺杂铁，我们抑制了镍钛基基体在剧烈变形加工过程中典型的变形诱发的非晶化。常见的(111)NiTi//(110)Nb 纹理被抑制，取而代之的是(110)NiTiFe//(110)Nb 纹理。这种纹理的变化使铌纳米线在镍钛铁基体中的温度高达 700°C 时仍能保持其完整性，而在同类基体中的温度仅为 550°C。模拟结果表明，铌纳米线热稳定性的增强归因于 (110)NiTiFe 和 (110)Nb 之间界面能的降低。此外，铁的掺杂还提高了铌扩散的迁移能垒，进一步阻止了碎裂和球化。

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