Vacuum最新文献

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Investigating the tribological behavior of bioinspired surfaces in agro-waste and alumina reinforced AA6063 matrix composites 研究农业废弃物和氧化铝增强 AA6063 基复合材料中生物启发表面的摩擦学行为

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2024-09-26 DOI: 10.1016/j.vacuum.2024.113687

The tribological behavior of three bioinspired (BI) agro-waste ashes—bean pod ash (BPA), cassava peel ash (CPA), and coconut husk ash (CHA)—integrated as reinforcements in an alumina-reinforced AA6063 matrix hybrid and monolithic composite was investigated. Studies utilizing agro-wastes for bioinspired surfaces are limited despite these wastes posing significant environmental challenges. Consequently, there has been a growing effort to valorize these residues for sustainable engineering applications. This study uses a two-step stir-casting methodology to engineer bioinspired materials with lightweight properties, exceptional hardness, and wear-resistant characteristics. Microstructural investigations revealed a homogeneous distribution of natural and synthetic reinforcements within the AA6063 matrix. Lightweight AMCs were successfully fabricated, exhibiting densities ranging from 2.57 to 2.74 g/cm³ and hardness values between 81.28 and 107.47 BHN. The average surface roughness of these composites varied from 2.4 to 3.4 μm, with ANOVA tests confirming a statistically significant difference (p < 0.005). Wear rates and the coefficient of friction were observed to range from 2.52 x 10⁻³ to 5.50 x 10⁻³ mm³/m and 0.2476 to 0.5403, respectively. Reinforcing the AA6063 alloy with bioinspired agro-wastes significantly enhanced the hardness and tribological performance of the as-cast BI-AMCs. Notably, the wear rates and friction coefficients were significantly reduced, with the monolithic BI-AMCs demonstrating superior results. Furthermore, adding bioinspired agro-wastes, such as BPA, CPA, and CHA, improved the surface texture of AA6063 more effectively than Al₂O₃, leading to slightly smoother surfaces. These nuanced bioinspired tribological behaviors present opportunities for tailored load-bearing and aesthetic applications derived from agro-waste-based composites. This study advances our understanding of bioinspired tribological phenomena and paves the way for the development of innovative materials with diverse applications and enhanced performance.

研究了三种生物启发（BI）农业废弃物灰烬--豆荚灰（BPA）、木薯皮灰（CPA）和椰子壳灰（CHA）--的摩擦学行为，这些灰烬作为增强材料被集成到氧化铝增强 AA6063 基质混合和整体复合材料中。利用农业废弃物制作生物启发表面的研究十分有限，尽管这些废弃物对环境构成了重大挑战。因此，越来越多的人开始努力将这些残留物用于可持续工程应用。本研究采用两步搅拌铸造法，设计出具有轻质特性、超强硬度和耐磨特性的生物启发材料。微结构研究表明，天然和合成增强材料在 AA6063 基体中分布均匀。成功制造出的轻质 AMC 密度介于 2.57 至 2.74 g/cm³ 之间，硬度值介于 81.28 至 107.47 BHN 之间。这些复合材料的平均表面粗糙度从 2.4 到 3.4 μm 不等，方差分析测试证实其差异具有统计学意义（p < 0.005）。磨损率和摩擦系数分别为 2.52 x 10-3 至 5.50 x 10-3 mm³/m 和 0.2476 至 0.5403。用生物农作物废弃物强化 AA6063 合金可显著提高铸造 BI-AMC 的硬度和摩擦学性能。值得注意的是，磨损率和摩擦系数明显降低，单片 BI-AMC 的效果更佳。此外，与 Al2O3 相比，添加双酚 A、CPA 和 CHA 等生物农产废料能更有效地改善 AA6063 的表面纹理，使其表面略微光滑。这些细微的生物启发摩擦学行为为基于农业废弃物的复合材料提供了量身定制的承重和美学应用机会。这项研究加深了我们对生物启发摩擦学现象的理解，为开发具有多样化应用和更高性能的创新材料铺平了道路。

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引用次数: 0

Ozone production in nanosecond pulsed dielectric barrier discharge in synthetic air: The effect of pulse width 纳秒脉冲介质阻挡放电在合成空气中产生臭氧：脉冲宽度的影响

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2024-09-26 DOI: 10.1016/j.vacuum.2024.113688

This work investigates the effect of pulse width on the characteristics of electrical discharge, optical emission spectra and ozone production in a water electrode DBD using a modulable nanosecond pulsed power supply. Results show that the increase of pulse width t_pw slightly increases the spectral intensity and the rotational temperature T_rot, with a typical T_rot of 299 ± 5 K at an applied peak voltage V_p of 18.6 kV and a t_pw of 400 ns. The electronic excitation temperature T_exc increases linearly with V_p and gradually with t_pw, while the electron density n_e shows a non-linear relationship with t_pw. Results also show that an increase in t_pw slightly increases the energy density. At low energy densities (SIE <50 J/L), increasing t_pw can improve ozone generation efficiency, reaching a maximum of 99.64 ± 0.87 g/kWh at 33.60 ± 1.53 J/L at a t_pw of 900 ns. This investigation provides substantial insight into the nanosecond pulsed ozone production.

本研究利用可调制纳秒脉冲电源研究了脉冲宽度对水电极 DBD 中放电特性、光发射光谱和臭氧产生的影响。结果表明，脉冲宽度 tpw 的增加会略微增加光谱强度和旋转温度 Trot，在应用峰值电压 Vp 为 18.6 kV 和 tpw 为 400 ns 时，典型的 Trot 为 299 ± 5 K。电子激发温度 Texc 随 Vp 线性增加，随 tpw 逐渐增加，而电子密度 ne 则与 tpw 呈非线性关系。结果还显示，tpw 的增加会略微提高能量密度。在低能量密度（SIE <50 J/L）条件下，增加 tpw 可提高臭氧生成效率，在 tpw 为 900 ns 时，当能量密度为 33.60 ± 1.53 J/L 时，臭氧生成效率最高可达 99.64 ± 0.87 g/kWh。这项研究为纳秒脉冲臭氧生产提供了实质性的启示。

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引用次数: 0

Cross-sectional surface analysis of magnetic domains, microstructures, and magnetic properties of the low-temperature phase MnBi prepared by low-temperature vacuum sintering 低温真空烧结制备的低温相锰硼的磁畴、微结构和磁性能的截面分析

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2024-09-26 DOI: 10.1016/j.vacuum.2024.113685

In this work, the low-temperature phase MnBi prepared by a low-temperature vacuum sintering process at 325 °C was studied. We found a significant increase in the energy product from 2.63 MGOe in the 12-h sintered sample to 3.64 MGOe in the 48-h sintered sample. This improvement is attributed to the solid-liquid diffusion process. Cross-sectional scanning electron microscopy (SEM) reveals that MnBi forms at the external surface of Mn particles and along interior surfaces, notably within cracks. Transmission electron microscopy further demonstrates that the Mn ratio increases and Bi decreases with distance from the crack. The selected area diffraction showed variations in the Mn ratio with distance from cracks and identified both Bi and MnBi phases in the MnBi layer. Magnetic force microscopy (MFM) analysis exhibited large phase shifts indicating repulsive or attractive forces in single ferromagnetic domains. This provides valuable insight into magnetic domains in the MnBi regions near Mn cracks. The MnBi formation model, developed for the vicinity of single cracks with uniform MnBi content, partly explains the magnetic interactions and phase shifts observed near these cracks. These findings provide significant insights into the MnBi microstructural and magnetic properties, potentially useful in tailoring and engineering magnetic structures.

在这项工作中，我们研究了通过 325 °C 低温真空烧结工艺制备的低温相 MnBi。我们发现能积从 12 小时烧结样品的 2.63 MGOe 显著增加到 48 小时烧结样品的 3.64 MGOe。这一改进归因于固液扩散过程。横截面扫描电子显微镜（SEM）显示，锰铍在锰颗粒的外表面和内表面形成，尤其是在裂缝内。透射电子显微镜进一步表明，随着与裂纹距离的增加，锰的比率增加，而铋的比率减少。选区衍射显示了锰比随裂纹距离的变化，并确定了锰铋层中的铋相和锰铋相。磁力显微镜（MFM）分析显示出较大的相移，表明单个铁磁畴中存在排斥力或吸引力。这为深入了解锰裂纹附近锰铋区域的磁畴提供了宝贵的信息。针对锰铋含量均匀的单个裂纹附近开发的锰铋形成模型，部分解释了在这些裂纹附近观察到的磁相互作用和相移。这些发现为了解锰铋的微观结构和磁性能提供了重要依据，可能有助于磁性结构的定制和工程设计。

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引用次数: 0

Effect of process parameters on residual gas in metal package 工艺参数对金属包装中残余气体的影响

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2024-09-26 DOI: 10.1016/j.vacuum.2024.113686

The effect of process parameters on the residual gases, H₂O, O₂, CO₂ and H₂ in the metal package were investigated in this study. It was found that the H₂O mainly came from the surface adsorption of raw materials and the H₂ was from the electroplated Ni/Au layers of Kovar alloy. The O₂ primarily came from the water vapor and the environment, while the CO₂ in the cavity was mainly generated by the reaction between the O₂ and residual carbon. The temperature and holding time of the baking, parallel seam welding and screening aging process could effectively affect the content of H₂O, O₂, H₂ and CO₂ in the cavity. Prior to sealing, increasing the temperature of baking and parallel seam welding could reduce the contents of H₂O, O₂ and H₂. However, after sealing, the H₂O and H₂ absorbed on the material surfaces continued to desorb into the sealed cavity during the screening aging process, leading to the increase of the H₂O and H₂ content. It was also found that the gas leakage has an important effect on the residual gas inside the cavity. In the long-term screening aging process, the O₂ could leak into the cavity from the air because of the concentration gradient. In the meantime, the O₂ reacted with the residual carbon to generate CO₂, causing an increase in the CO₂ content. As the CO₂ concentration in the cavity was higher than that in the air, it would leak into the air until equilibrium was reached.

本研究调查了工艺参数对金属包中残留气体 H2O、O2、CO2 和 H2 的影响。研究发现，H2O 主要来自原材料的表面吸附，而 H2 则来自 Kovar 合金的电镀 Ni/Au 层。O2 主要来自水蒸气和环境，而空腔中的 CO2 主要由 O2 和残碳反应生成。烘烤、平行缝焊接和筛选老化过程的温度和保温时间可有效影响型腔中 H2O、O2、H2 和 CO2 的含量。密封前，提高烘烤和平行缝焊接的温度可降低 H2O、O2 和 H2 的含量。然而，密封后，材料表面吸收的 H2O 和 H2 在筛选老化过程中继续解吸到密封腔中，导致 H2O 和 H2 含量增加。研究还发现，气体泄漏对空腔内的残余气体有重要影响。在长期筛选老化过程中，由于浓度梯度的存在，O2 可能会从空气中泄漏到空腔中。同时，O2 与残碳反应生成 CO2，导致 CO2 含量增加。由于空腔中的二氧化碳浓度高于空气中的浓度，二氧化碳会渗入空气中，直至达到平衡。

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引用次数: 0

Study of thermodynamic properties and elastic constants of cubic boron nitride by statistical moment method 用统计矩法研究立方氮化硼的热力学性质和弹性常数

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2024-09-26 DOI: 10.1016/j.vacuum.2024.113663

The statistical moment method has been applied to investigate temperature effects on the thermodynamic and elastic properties of the cubic boron nitride (cBN). The analytical expressions of thermal-induced atomic displacement, the mean-square displacement, elastic constants (Young’s modulus, bulk modulus, shear modulus, and longitudinal-wave elastic constant), and the bulk and longitudinal sound velocities of cBN compound have been derived. Our theoretical calculations are compared with previous experiments and computations showing reasonable agreement. We have shown that while the mechanical strength and Debye temperature of the cBN material are slightly reduced as temperature rises, the mean-square displacement function increases rapidly. The noticeable difference in mean-square displacements of B isotopes is observed at low temperature, and the disparity diminishes gradually at high temperatures. The calculations of the present work can be used as an appropriate reference for the future experiments.

我们采用统计矩法研究了温度对立方氮化硼（cBN）热力学和弹性特性的影响。得出了立方氮化硼化合物的热诱导原子位移、均方位移、弹性常数（杨氏模量、体积模量、剪切模量和纵波弹性常数）以及体积声速和纵波声速的解析表达式。我们的理论计算结果与之前的实验和计算结果进行了比较，结果显示两者吻合。我们的研究表明，虽然随着温度的升高，cBN 材料的机械强度和德拜温度略有降低，但其均方位移函数却迅速增加。B 同位素的均方位移在低温下有明显差异，在高温下差异逐渐减小。本研究的计算结果可作为今后实验的适当参考。

引用次数: 0

Mechanical property improvement of diffusion bonded ZrCx joints by chemical homogenization using Ta as the interlayer 使用 Ta 作为中间层，通过化学均匀化改善扩散粘接 ZrCx 接头的机械性能

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2024-09-25 DOI: 10.1016/j.vacuum.2024.113684

In the present study, a transition metal Ta foil was used as the interlayer to diffusion bond ZrC_x ceramics. A needle-like ζ-Ta₄C_3-x phase was initially formed at the interface and could be effectively dissolved into the base ceramic by reasonably tuning the bonding temperature and holding time, resulting in a chemically homogeneous joint when diffusion bonded at 1600 °C for 1 h under 20 MPa pressure. The composition of the homogeneous joints was composed of ZrC_x(Ta), which is very similar to the base ceramic. The ζ-Ta₄C_3-x phase was found beneficial to the mechanical property of the joints due to its mechanically interlocking effect and the ability to absorb the propagation energy of microcracks. The chemically homogeneous joint had comparable four-point bending strength and nano-indentation hardness with that of the base ceramic, indicating that chemical homogenization of the joint has great potential to enhance the mechanical property of the ZrC_x joints.

在本研究中，过渡金属 Ta 箔被用作扩散粘合 ZrCx 陶瓷的中间层。界面上最初形成了针状的 ζ-Ta4C3-x 相，通过合理调节键合温度和保温时间，可有效地将其溶解到基底陶瓷中，从而在 20 兆帕压力下于 1600 ℃ 扩散键合 1 小时后形成化学均匀的接合点。均质接头的成分是 ZrCx(Ta)，与基底陶瓷非常相似。由于ζ-Ta4C3-x 相具有机械互锁效应和吸收微裂纹扩展能量的能力，因此有利于提高接缝的机械性能。化学均质接头的四点弯曲强度和纳米压痕硬度与基底陶瓷相当，这表明接头的化学均质化在提高 ZrCx 接头的机械性能方面具有巨大潜力。

引用次数: 0

The migration behaviour of strontium co-implanted with helium into SiC at room temperature and annealed at temperatures above 1000 °C 锶与氦在室温下共同植入碳化硅并在 1000 °C 以上温度下退火的迁移行为

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2024-09-24 DOI: 10.1016/j.vacuum.2024.113676

The study investigated the migration behaviour of Sr implanted into SiC in the presence of helium (He). Sr ions were implanted into polycrystalline SiC samples (Sr-SiC) at room temperature (RT), and co-implanted with He ions also at RT (Sr + He-SiC). The samples were then annealed isochronally at 1100 °C, 1200 °C, and 1300 °C for 5 h. Transmission electron microscopy (TEM) and Rutherford backscattering spectrometry (RBS) were used to characterize both as-implanted and annealed annealed samples. Sr implantation induced amorphization of SiC, while co-implantation with He led to the formation of He nano-bubbles within the amorphous SiC matrix. During annealing, Sr migrated towards the surface, resulting in loss of Sr, cavity formation, and formation of Sr precipitates in the Sr-SiC samples. In Sr + He-SiC samples, He-induced cavities formed around the projected range of Sr, inhibiting epitaxial regrowth of SiC. As a result, the Sr distribution became concentrated around these He cavities, with Sr trapped both in front and behind them. The enhanced migration of Sr in annealed Sr + He-SiC is attributed to the slower recrystallization of the damaged SiC layer, the presence of larger He-induced cavities, and increased surface roughness. These findings provide insights into Sr migration the mechanisms in SiC, relevant for enhancing the safety of nuclear fuels.

本研究调查了在氦（He）存在的情况下将锶植入碳化硅中的迁移行为。在室温（RT）下将硒离子植入多晶 SiC 样品（Sr-SiC），并在室温（RT）下与氦离子共同植入（Sr + He-SiC）。采用透射电子显微镜（TEM）和卢瑟福背散射光谱仪（RBS）对植入后和退火后的样品进行表征。Sr 植入会导致碳化硅发生非晶化，而与 He 共同植入则会在非晶碳化硅基体中形成 He 纳米气泡。在退火过程中，Sr 向表面迁移，导致 Sr-SiC 样品中的 Sr 损失、空腔形成和 Sr 沉淀的形成。在 Sr + He-SiC 样品中，He 引发的空腔在 Sr 的投影范围周围形成，抑制了 SiC 的外延再生长。因此，硒的分布集中在这些氦空穴周围，硒被截留在氦空穴的前面和后面。在退火的 Sr + He-SiC 中，Sr 的迁移增强，这归因于受损 SiC 层的再结晶速度减慢、存在更大的 He 引发的空穴以及表面粗糙度增加。这些发现有助于深入了解碳化硅中的硒迁移机制，从而提高核燃料的安全性。

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引用次数: 0

Ab initio molecular dynamics investigation on hydrogen diffusion behavior in liquid aluminum alloy melts 液态铝合金熔体中氢扩散行为的 Ab initio 分子动力学研究

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2024-09-24 DOI: 10.1016/j.vacuum.2024.113683

In this work, ab initio molecular dynamics (AIMD) simulations under both NVT and NPT ensembles were performed to study the influence of alloying elements of Mg, Fe, Si, Ti, Cu, Zn, F, and Cl on the H diffusion behavior in liquid aluminum melt. It is found that the diffusion coefficient of H simulated by AIMD under the NVT model is highly consistent with the reported experimental results. Specifically, the addition of Cu, Cl, Si, and Zn is inclined to increase the diffusion coefficient of H in the melt, whereas the opposite result is observed with the addition of F, Fe, and Ti. Moreover, it is proved that the H diffusion coefficients are positively correlated with the H-Al bond lengths and the coordination number of H in a constant volume system. The obtained results deepen the understanding of the diffusion of H atoms in Al melts and contribute to the optimization of existing melt purification technologies.

本研究在 NVT 和 NPT 组合下进行了原子分子动力学模拟（AIMD），以研究 Mg、Fe、Si、Ti、Cu、Zn、F 和 Cl 等合金元素对液态铝熔体中 H 扩散行为的影响。结果发现，在 NVT 模型下，AIMD 模拟的 H 扩散系数与实验结果高度一致。具体来说，添加 Cu、Cl、Si 和 Zn 会增加 H 在熔体中的扩散系数，而添加 F、Fe 和 Ti 则会出现相反的结果。此外，研究还证明，在恒定体积体系中，H 的扩散系数与 H-Al 键长度和 H 的配位数呈正相关。研究结果加深了人们对铝熔体中 H 原子扩散的理解，有助于优化现有的熔体净化技术。

引用次数: 0

Tb-doped borosilicate glass scintillators with high thermal stability for high-resolution X-ray imaging 用于高分辨率 X 射线成像的高热稳定性掺铽硼硅酸盐玻璃闪烁体

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2024-09-24 DOI: 10.1016/j.vacuum.2024.113677

Scintillators with high thermal stability and excellent spatial resolution are desirable for X-ray imaging applications in harsh environments. Here, Tb³⁺-doped borosilicate glass scintillators were prepared using conventional melt-quenching method. The optimized Tb³⁺-doped borosilicate glass (G-15Tb) scintillator exhibited a significantly higher X-ray excited luminescence intensity (147 % of Bi₄Ge₃O₁₂). Furthermore, it possessed a remarkable imaging spatial resolution of 20 lp/mm, surpassing the standard requirement for X-ray imaging and medical computed tomography scans (2 lp/mm). Moreover, the X-ray excited luminescence intensity of G-15Tb glass sample remained unchanged even after being submerged in water for 30 days, indicating exceptional water resistance. Additionally, the integral intensity of photoluminescence at 573 K is 96.7 % of its initial value. Most importantly, the G-15Tb glass scintillator remains high-quality X-ray images even at elevated operating temperatures. Therefore, the Tb³⁺-doped borosilicate glass scintillator holds immense potential for high-resolution X-ray imaging in harsh environments.

具有高热稳定性和出色空间分辨率的闪烁体是恶劣环境中 X 射线成像应用的理想之选。本文采用传统的熔淬法制备了掺杂 Tb3+ 的硼硅玻璃闪烁体。优化后的掺 Tb3+ 硼硅酸盐玻璃闪烁体（G-15Tb）具有更高的 X 射线激发发光强度（Bi4Ge3O12 的 147%）。此外，它的成像空间分辨率高达 20 lp/mm，超过了 X 射线成像和医学计算机断层扫描的标准要求（2 lp/mm）。此外，即使在水中浸泡 30 天，G-15Tb 玻璃样品的 X 射线激发发光强度仍保持不变，这表明它具有优异的耐水性。此外，573 K 时的光致发光积分强度是其初始值的 96.7%。最重要的是，即使在较高的工作温度下，G-15Tb 玻璃闪烁体仍能保持高质量的 X 射线图像。因此，掺杂 Tb3+ 的硼硅酸盐玻璃闪烁体在恶劣环境下进行高分辨率 X 射线成像方面具有巨大的潜力。

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引用次数: 0

Molecular dynamics simulation of mechanical properties of NiCo alloy under primary cascade damage 一次级联损伤下镍钴合金机械性能的分子动力学模拟

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2024-09-24 DOI: 10.1016/j.vacuum.2024.113681

Investigating the performance of single-phase solid solution alloys (SP-CSAs) after cascade damage is of significant importance for their industrial applications. This study employs molecular dynamics simulations to investigate the cascade process of a typical NiCo SP-CSA at different primary knock-on atom (PKA) energies and the subsequent effects on mechanical properties. It is found that as the PKA energy increases, the number of defects increases linearly, the size of the defect clusters grows, and most of the defects are caused by the displacement of Ni atoms. However, the yield strain and yield strength of the cascaded NiCo alloys decreased significantly during the subsequent tensile process, and the decrease increased with the increase of PKA energy. This is mainly because cascade-induced point defects become nucleation sites for dislocations with the application of strain, leading to premature plastic deformation of the alloy and altering their deformation modes. This ultimately results in significant degradation of mechanical properties. These findings offer theoretical insights for designing new reactor materials with enhanced irradiation resistance.

研究单相固溶合金（SP-CSA）在级联损伤后的性能对其工业应用具有重要意义。本研究采用分子动力学模拟来研究典型的镍钴 SP-CSA 在不同原生击穿原子（PKA）能量下的级联过程及其对机械性能的影响。研究发现，随着 PKA 能量的增加，缺陷的数量呈线性增加，缺陷簇的尺寸增大，且大部分缺陷是由镍原子的位移引起的。然而，在随后的拉伸过程中，级联镍钴合金的屈服应变和屈服强度明显下降，且下降幅度随 PKA 能量的增加而增大。这主要是因为级联引发的点缺陷在施加应变时成为位错的成核点，导致合金过早发生塑性变形并改变其变形模式。这最终会导致机械性能显著下降。这些发现为设计抗辐照能力更强的新型反应堆材料提供了理论依据。

引用次数: 0

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