Materials Science and Engineering: A最新文献_第8页

Effect of pulse current on the creep ageing behavior of pre-strained 2195 Al-Li alloy 脉冲电流对预应变 2195 Al-Li 合金蠕变时效行为的影响

IF 6.1 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2024-10-28 DOI: 10.1016/j.msea.2024.147468

Yongqian Xu , Shiru Yu , Bolin Ma , Shugen Luo , Shengmeng Hui , Chang Zhou , Lihua Zhan , Minghui Huang

Pre-strained aluminum lithium (Al-Li) alloy plates have ultra-high strength and comprehensive performance after aging treatments, and are widely used in the aerospace industry. The initial increase in dislocation density caused by these pre-strains will significantly affect the evolution of deformation, microstructure, and mechanical properties during the pulse current assisted creep ageing forming process. Therefore, the effect of pulse current on the creep ageing behavior of 2195 Al-Li alloy with different pre-strains (0 %, 4 %, and 8 %) was investigated. As the pulse current increases within the first 1h creep aging process of the various pre-strain samples, the 1h creep strain significantly increases and the subsequent steady-state creep rate slightly reduce. Moreover, the larger the pre-strain, the higher the total creep strain. Pulse current promotes the movement and recovery of initial dislocations, and promotes the fine formation of T₁ phase and suppresses the nucleation of θ′ and

δ^{'}

phase, thereby improving mechanical properties. Compared with the conventional creep ageing process, the pulse current acting on pre-strained 2195 Al-Li alloy significantly increased the peak aged strengthen and shorten the peak aging time. Meanwhile, the peak time platform period has also been significantly extended. It is evident that the application of pulse current assisted creep ageing forming process to pre-strained 2195 Al-Li alloy plates can significantly improve formability and mechanical properties, enlarges the forming process window and realize collaborative manufacturing of Al-Li alloy component shape and performance.

预应变铝锂（Al-Li）合金板在时效处理后具有超高强度和综合性能，被广泛应用于航空航天工业。在脉冲电流辅助蠕变时效成形过程中，这些预应变引起的初始位错密度增加将显著影响变形、微观结构和力学性能的演变。因此，研究了不同预应变（0%、4% 和 8%）下脉冲电流对 2195 Al-Li 合金蠕变时效行为的影响。在不同预应变样品的前 1 小时蠕变时效过程中，随着脉冲电流的增加，1 小时蠕变应变显著增加，随后的稳态蠕变速率略有降低。此外，预应变越大，总蠕变应变越高。脉冲电流促进了初始位错的移动和恢复，促进了 T1 相的精细形成，抑制了 θ′ 和 δ′ 相的成核，从而改善了力学性能。与传统蠕变时效工艺相比，脉冲电流作用于预应变 2195 Al-Li 合金可显著提高峰值时效强化，缩短峰值时效时间。同时，峰值时间平台期也明显延长。由此可见，在预应变 2195 Al-Li 合金板材上应用脉冲电流辅助蠕变时效成形工艺，可显著改善成形性和力学性能，扩大成形工艺窗口，实现 Al-Li 合金构件形状和性能的协同制造。

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引用次数: 0

HIP effect on the high-temperature creep behavior of a solution-treated nickel-based single crystal superalloy HIP 对溶液处理镍基单晶超级合金高温蠕变行为的影响

IF 6.1 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2024-10-28 DOI: 10.1016/j.msea.2024.147470

Siliang He , Longfei Li , Song Lu , Yunsong Zhao , Jian Zhang , Qiang Feng

Micropores and residual eutectics are detrimental to the creep behavior of the nickel-based single crystal (SX) superalloys. The decrease of residual eutectics and micropores in the interdendritic regions by hot isostatic pressing (HIP) can improve the creep rupture life of nickel-based SX superalloy. In this work, the influence of HIP temperature and pressure on the creep rupture life as well as the impact of HIP treatment on creep behavior of nickel-based SX superalloy with solution-treated state at 980 °C/250 MPa were studied. The results show that the improvement of creep rupture life was primarily due to the prolongation of the slow-accelerating creep stage. Increasing HIP temperature from 1280 °C to 1300 °C can raise the creep rupture lives of the HIP-treated samples. During creep, the micropores inside the non-HIP sample increased continuously, whereas that of the HIP-treated sample had little change until creep rupture. The HIP-treated sample had relatively weak plastic deformation in the interdendritic regions compared with the non-HIP sample, suppressing the microcrack initiation and propagation at the end of creep. This study is beneficial for developing a method to improve the creep performance of nickel-based SX superalloys at high temperatures.

微孔和残余共晶不利于镍基单晶（SX）超级合金的蠕变行为。通过热等静压（HIP）减少残余共晶和树枝状晶间区的微孔可以提高镍基 SX 超合金的蠕变断裂寿命。在这项工作中，研究了 HIP 温度和压力对蠕变断裂寿命的影响，以及 HIP 处理对在 980 °C/250 MPa 溶液处理状态下的镍基 SX 超合金蠕变行为的影响。结果表明，蠕变断裂寿命的提高主要是由于慢速蠕变阶段的延长。将 HIP 温度从 1280 °C 提高到 1300 °C 可以提高 HIP 处理样品的蠕变断裂寿命。在蠕变过程中，非 HIP 样品内部的微孔不断增加，而经 HIP 处理的样品在蠕变断裂前几乎没有变化。与非 HIP 样品相比，HIP 处理过的样品在树枝间区域的塑性变形相对较弱，从而抑制了蠕变末期微裂纹的产生和扩展。这项研究有助于开发一种方法来改善镍基 SX 超合金在高温下的蠕变性能。

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引用次数: 0

Microstrain partitioning, transformation induced plasticity, and damage evolution of a third generation medium Mn advanced high strength steel 第三代中锰高级高强度钢的微应变分配、转变诱导塑性和损伤演化

IF 6.1 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2024-10-26 DOI: 10.1016/j.msea.2024.147447

Concetta Pelligra , Babak Shalchi Amirkhiz , Nafiseh Zafer , Jidong Kang , David S. Wilkinson

An experimental Medium Mn (med-Mn) steel (0.15C-5.8Mn-1.8Al-0.71Si) with a martensitic starting microstructure, intercritically annealed at 685 °C for 120s, was discovered to have a large true strain at fracture (ɛ_f = 0.61) while also meeting established (strength x elongation) targets (28,809 MPa%), sustained monotonic work hardening and prolonged Transformation Induced Plasticity (TRIP) kinetics. This was found by varying the intercritical annealing (IA) temperature within a narrow temperature interval in order to isolate its impact on TRIP kinetics and damage development on such med-Mn steel. A comprehensive understanding of the microstructural damage processes leading to fracture is presented using quasi in-situ Scanning Electron Microscope tensile testing as well as X-ray Computed Microtomography. In addition, we precisely evaluated the TRIP kinetics of this steel using a combined Digital Image Correlation (DIC) and synchrotron-sourced High Energy X-ray Diffraction technique. With these methods, we demonstrate that an abundance of voids nucleate during deformation, but their growth can be suppressed by prolonging TRIP over a large strain range. Moreover, novel post-processing techniques to assess DIC acquired data at the microscopic scale have been used to gauge the severity of strain partitioning amongst phases and strain gradient evolution across dissimilar phase interfaces. By comparing it to another 3G TRIP-assisted steel and an ultrafine grained Dual Phase steel. Overall, it has been found that, in addition to carefully moderating TRIP kinetics, the introduction of polygonal ferrite, as is conventional in med-Mn steels, enhances the local forming properties and damage tolerance in 3G TRIP-assisted microstructures.

一种具有马氏体起始显微组织的实验性中锰钢（0.15C-5.8Mn-1.8Al-0.71Si）在 685 °C 下进行 120s 的中间退火，发现其断裂时具有较大的真实应变（ɛf = 0.61），同时还满足既定的（强度 x 伸长率）目标（28,809 MPa%）、持续的单调加工硬化和较长的变形诱导塑性（TRIP）动力学。通过在较窄的温度区间内改变临界退火（IA）温度，我们发现了这一点，目的是隔离临界退火温度对中锰钢 TRIP 动力学和损伤发展的影响。我们利用准原位扫描电子显微镜拉伸测试和 X 射线计算机显微层析技术，全面了解了导致断裂的微观结构损伤过程。此外，我们还利用数字图像相关性（DIC）和同步辐射源高能 X 射线衍射技术，对这种钢的 TRIP 动力学进行了精确评估。通过这些方法，我们证明在变形过程中会产生大量空洞，但通过在较大应变范围内延长 TRIP 可以抑制空洞的生长。此外，我们还采用了新颖的后处理技术来评估微观尺度上的 DIC 采集数据，以衡量各相之间应变分化的严重程度以及不同相界面上应变梯度的演变情况。通过将其与另一种 3G TRIP 辅助钢和超细晶粒双相钢进行比较。总之，研究发现，除了精心调节 TRIP 动力学之外，按照中锰钢的传统做法引入多边形铁素体还能增强 3G TRIP 辅助微结构的局部成形性能和损伤耐受性。

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引用次数: 0

Study on the material flow behavior, microstructure evolution and strengthening mechanism of arc-assisted friction stir weld of Ti6321 alloy Ti6321 合金电弧辅助搅拌摩擦焊缝的材料流动行为、微观结构演变和强化机理研究

IF 6.1 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2024-10-26 DOI: 10.1016/j.msea.2024.147455

Guangda Sun , Li Zhou , Yuxuan Li , Zhongxian Yan , Xiaoguo Song , Fuyang Gao , Xiangqian Liu , Zhiqian Liao

In this study, 6 mm thick Ti6321 alloy plates were butt welded using conventional friction stir welding (FSW) and arc-assisted friction stir welding (AAFSW). The defect formation and suppression, microstructure evolution, and plastic deformation and failure mechanisms of the joints were systematically studied. The results showed that a defect-free joint could be achieved with a significant reduction of 50 % in both axial and forward forces for AAFSW. The formation of the bottom defect was attributed to the non-convergence of vertical flow components and the circumferential flow along the pin. The applied arc enhances the material flow along the thickness direction, thereby promoting the transformation of the microstructure at the bottom of the stir zone (SZ) from a bimodal structure to a fully lamellar structure. Texture analysis reveals a shift from B and Y₂ to C₁ components with increased heat input and strain. Plastic deformation in the SZ is primarily dominated by slip, accompanied by twinning deformation in both joints. And the mechanism involving dislocation decomposition and stacking fault formation leading to dynamic phase transformations has been further confirmed. The AAFSW joint exhibits a more uniform hardness distribution and higher joint efficiency (96 %) with an average ultimate tensile strength (UTS) of 771 MPa and an elongation of 7.8 %. The joint failure mechanism is influenced by microhardness and uncoordinated plastic deformation arising from dislocation slip and twinning effects along the thickness. These insights confirm that AAFSW is a new choice for achieving efficient and high-quality connections in medium-thick Ti alloys.

本研究采用传统搅拌摩擦焊（FSW）和电弧辅助搅拌摩擦焊（AAFSW）对 6 毫米厚的 Ti6321 合金板进行了对接焊接。系统研究了接头的缺陷形成和抑制、微观结构演变、塑性变形和失效机理。结果表明，AAFSW 可实现无缺陷接头，其轴向力和正向力均显著降低了 50%。底部缺陷的形成归因于垂直流动分量和沿销轴的圆周流动不融合。施加的电弧增强了材料沿厚度方向的流动，从而促进了搅拌区（SZ）底部的微观结构从双峰结构转变为全片状结构。纹理分析表明，随着热输入和应变的增加，B 和 Y2 组份向 C1 组份转变。SZ 中的塑性变形主要以滑移为主，并伴随着两个接合处的孪生变形。位错分解和堆积断层形成导致动态相变的机制得到了进一步证实。AAFSW 接头的硬度分布更均匀，接头效率更高（96%），平均极限拉伸强度（UTS）为 771 兆帕，伸长率为 7.8%。接合失效机制受微硬度和不协调塑性变形的影响，而不协调塑性变形则是由位错滑移和沿厚度方向的孪生效应引起的。这些研究结果证实，AAFSW 是实现中厚钛合金高效、高质量连接的新选择。

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引用次数: 0

Preparation of a novel high-entropy alloy AlNbTiVZr with excellent strength and ductility: The effect of Zr composition on microstructure and properties 制备具有优异强度和延展性的新型高熵合金 AlNbTiVZr：Zr 成分对微观结构和性能的影响

IF 6.1 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2024-10-26 DOI: 10.1016/j.msea.2024.147441

Yuchi Fang, Zhangping Hu, Jinsheng Ji, Longxiang Sun, Leilei Wang, Xiaohong Zhan

Light-weight refractory high-entropy alloys with low density and good ductility are widely used in various engineering fields. Despite their potential, achieving an optimal strength-ductility balance in these lightweight alloys remains an emerging field of study. In this study, Al_0.8Nb_0.5Ti₂V₂Zr_x (x = 0, 0.3, 0.6, and 0.9) alloys were prepared by vacuum arc melting. A comprehensive evaluation of their microstructure, density, hardness, and compressive behavior at both room and 873 K temperatures was conducted. The introduction of Zr transforms the alloy phase structure from body-centered cubic (BCC) to BCC + C14-Laves. The areal fraction of the C14-Laves phase increased from 0 % to 32.47 % with increasing Zr content from x = 0 to 0.9, respectively. Furthermore, the Zr content had an obvious effect on the mechanical properties of the alloys. The compressive strength and hardness of the alloys improved, but the ductility simultaneously decreased, with increasing Zr content. The yield strengths of the alloys with x = 0, 0.3, 0.6, and 0.9 reached 971, 1216, 1483, and 1714 MPa, respectively, at room temperature, and 946, 1287, 1319, and 1469 MPa, respectively, at 873 K. In addition, the alloys maintained their deformation resistance and good ductility at 873 K. In particular, the Al_0.8Nb_0.5Ti₂V₂Zr_0.3 exhibited a good balance between strength and ductility at room and 873 K temperatures due to the strengthening effect of a granular secondary phase. Upon comparison with other reported high-entropy alloys, the Al_0.8Nb_0.5Ti₂V₂Zr_x series showcased superior specific yield strength and ductility.

具有低密度和良好延展性的轻质耐火高熵合金被广泛应用于各个工程领域。尽管这些轻质合金潜力巨大，但如何实现强度与延展性的最佳平衡仍是一个新兴的研究领域。本研究采用真空电弧熔炼法制备了 Al0.8Nb0.5Ti2V2Zrx（x = 0、0.3、0.6 和 0.9）合金。对它们在室温和 873 K 温度下的微观结构、密度、硬度和抗压性能进行了全面评估。Zr 的引入使合金相结构从体心立方（BCC）转变为 BCC + C14-Laves。随着 Zr 含量从 x = 0 到 0.9 的增加，C14-Laves 相的面积分数分别从 0 % 增加到 32.47 %。此外，锆含量对合金的机械性能也有明显的影响。随着锆含量的增加，合金的抗压强度和硬度提高，但延展性同时降低。x=0、0.3、0.6 和 0.9 的合金在室温下的屈服强度分别达到了 971、1216、1483 和 1714 兆帕，在 873 K 下的屈服强度分别达到了 946、1287、1319 和 1469 兆帕。特别是 Al0.8Nb0.5Ti2V2Zr0.3，由于粒状次生相的强化作用，在室温和 873 K 温度下都能很好地平衡强度和延展性。与其他已报道的高熵合金相比，Al0.8Nb0.5Ti2V2Zrx 系列具有更高的比屈服强度和延展性。

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引用次数: 0

Enhancing strength and toughness in a pearlitic rail steel via multi-alloying and accelerated cooling 通过多元合金化和加速冷却提高珠光体轨道钢的强度和韧性

IF 6.1 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2024-10-24 DOI: 10.1016/j.msea.2024.147444

Shaohua Li , Junheng Gao , Zhenyu Han , Haibo Feng , Chongmu Chen , Haitao Zhao , Shuize Wang , Kexiao Wang , Guilin Wu , Honghui Wu , Xinping Mao

The demand for higher speeds and heavier loads has emphasized the necessity to tackle the inherent trade-off between strength and toughness in pearlitic rail steels. Herein, the co-additions of Cr, Ni and Cu and accelerated cooling rate on the microstructure and mechanical properties of a medium carbon pearlitic steel were systematically investigated. In comparison with base alloy, the new steel exhibits smaller prior austenite grain size (PAGS) due to the drag effect of Cu and Ni solutes. The finer PAGS and lower C content increased the volume fraction of proeutectoid ferrite. The finer pearlitic nodule size (PNS) and pearlitic colony size (PCS) were attributed to the small PAGS and greater extent of undercooling due to the combined effect of multi-alloying and accelerated cooling. Additionally, the synergistic effects of multi-alloying and accelerated cooling rate decrease the pearlitic phase transformation temperature, accountable for the finer interlamellar spacing (IS). Compared with the base steel, the yield strength and ultimate tensile strength of the new steel increased from 587 MPa to 1069 MPa to 740 MPa and 1178 MPa, respectively, with a simultaneous increase of ductility from 12.4 % to 14.7 %. The strength increments are mainly attributed to the finer IS in the new steel. Meanwhile, the new steel possesses a higher impact toughness compared to the base steel due to the increased volume fraction of proeutectoid ferrite, and finer PNS and IS.

对更高转速和更重负荷的需求强调了解决珠光体轨道钢强度和韧性之间固有权衡的必要性。本文系统研究了铬、镍和铜的共同添加以及加速冷却速度对中碳珠光体钢微观结构和机械性能的影响。与基合金相比，由于铜和镍溶质的阻力作用，新钢的先奥氏体晶粒尺寸（PAGS）更小。更细的 PAGS 和更低的 C 含量增加了原共晶铁素体的体积分数。较细的珠光体结核尺寸（PNS）和珠光体菌落尺寸（PCS）归因于较小的 PAGS 以及多重合金化和加速冷却共同作用下较大的欠冷程度。此外，多元合金化和加速冷却的协同效应降低了珠光体相变温度，从而使珠光体晶间距（IS）更细。与基体钢相比，新钢的屈服强度和极限抗拉强度分别从 587 兆帕和 1069 兆帕提高到 740 兆帕和 1178 兆帕，延展性也从 12.4% 提高到 14.7%。强度的提高主要归功于新钢中更细的 IS。同时，由于原共晶铁素体的体积分数增加、PNS 和 IS 更细，与基体钢相比，新钢具有更高的冲击韧性。

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引用次数: 0

Enhancing strength, ductility, and thermal fatigue resistance in Stellite 21 coatings via Mn alloying and Transformation-Induced Plasticity 通过锰合金化和转化诱导塑性提高人造卫星 21 涂层的强度、延展性和抗热疲劳性

IF 6.1 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2024-10-24 DOI: 10.1016/j.msea.2024.147448

Yongsheng Zhao , Chuan Yang , Lei Wang , Ying Wu , Yan Liu , Zhengting Xie , Qiang Fang , Wei Feng , Haolin Liu , Hui Chen

This study investigates the effect of Mn on the microstructure and mechanical properties of Stellite 21 cobalt-based coatings prepared by laser cladding on 24CrNiMo steel substrates, focusing on utilizing the Transformation-Induced Plasticity (TRIP) mechanism to enhance toughness and thermal fatigue performance. The results indicate that the microstructure of the Stellite 21 alloy coating is primarily composed of γ-Co (FCC) with a minor presence of ε-Co (HCP), M₂₃C₆, and M₇C₃ carbides, which predominantly precipitate at or near the grain boundaries. Upon the addition of Mn, it dissolves into the γ-Co matrix, causing lattice distortion and increasing dislocation density, thereby contributing to solid solution strengthening. Compared to the Mn-free Stellite 21 alloy coating, the coating with 5 % Mn exhibits an approximately 21 % increase in tensile strength (∼1135 MPa) and a 74 % increase in elongation (∼14.5 %). This improvement is mainly attributed to the solid solution strengthening caused by lattice distortion due to Mn addition and the synergistic enhancement from the TRIP mechanism facilitated by the lower stacking fault energy. Moreover, the thermal fatigue crack propagation rate in the coating with 5 % Mn is reduced by approximately 42.5 % compared to the Mn-free Stellite 21 alloy coating. The enhancement in thermal fatigue performance is primarily due to the Mn addition, which stabilizes the ε-Co phase during thermal fatigue processes, enhancing plastic deformation capacity. The phase transformation process alleviates stress concentration, effectively reducing crack propagation rates and ultimately improving the material's thermal fatigue performance.

本研究探讨了锰对在 24CrNiMo 钢基体上通过激光熔覆制备的 Stellite 21 钴基镀层的微观结构和机械性能的影响，重点是利用转化诱导塑性（TRIP）机制来提高韧性和热疲劳性能。结果表明，Stellite 21 合金涂层的微观结构主要由 γ-Co (FCC) 组成，少量存在 ε-Co (HCP)、M23C6 和 M7C3 碳化物，这些碳化物主要析出在晶界处或晶界附近。添加锰后，锰会溶解到γ-Co基体中，导致晶格畸变和位错密度增加，从而促进固溶强化。与不含 Mn 的 Stellite 21 合金涂层相比，含 5% Mn 的涂层的抗拉强度提高了约 21%（∼1135 兆帕），伸长率提高了 74%（∼14.5%）。这种改善主要归因于添加锰后晶格畸变导致的固溶强化，以及较低的堆叠断层能促进 TRIP 机制的协同增强。此外，与不含 Mn 的 Stellite 21 合金涂层相比，含 5% Mn 的涂层的热疲劳裂纹扩展率降低了约 42.5%。热疲劳性能的提高主要是由于添加了锰，在热疲劳过程中稳定了ε-Co 相，从而提高了塑性变形能力。相变过程缓解了应力集中，有效降低了裂纹扩展率，最终提高了材料的热疲劳性能。

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引用次数: 0

Mechanical properties of pure elements from a comprehensive first-principles study to data-driven insights 从全面的第一性原理研究到数据驱动的纯元素机械特性见解

IF 6.1 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2024-10-24 DOI: 10.1016/j.msea.2024.147446

Shun-Li Shang , Michael C. Gao , Yi Wang , Jingjing Li , Allison M. Beese , Zi-Kui Liu

<div><div>Unraveling mechanical properties from fundamental is far from complete despite their vital role in determining applicability and longevity for a given material. Here, we perform a comprehensive study related to mechanical properties of 60 pure elements in bcc, fcc, hcp, and/or diamond structures by means of pure alias shear and pure tensile deformations via density functional theory (DFT) based calculations alongside a broad review of existing literature. The present data compilation enables a detailed correlation analysis of mechanical properties, focusing on DFT-based ideal shear and tensile strengths (<span><math><mrow><msub><mi>τ</mi><mtext>is</mtext></msub></mrow></math></span> and <span><math><mrow><msub><mi>σ</mi><mtext>it</mtext></msub></mrow></math></span>), stable and unstable stacking fault energies (<span><math><mrow><msub><mi>γ</mi><mtext>sf</mtext></msub></mrow></math></span> and <span><math><mrow><msub><mi>γ</mi><mtext>us</mtext></msub></mrow></math></span>), surface energy (<span><math><mrow><msub><mi>γ</mi><mi>s</mi></msub></mrow></math></span>), and vacancy activation energy (<span><math><mrow><msub><mi>Q</mi><mi>V</mi></msub></mrow></math></span>); and experimental hardness (<span><math><mrow><msub><mi>H</mi><mi>B</mi></msub></mrow></math></span>), ultimate tensile strength (<span><math><mrow><msub><mi>σ</mi><mtext>UT</mtext></msub></mrow></math></span>), fracture toughness (<span><math><mrow><msub><mi>K</mi><mtext>Ic</mtext></msub></mrow></math></span>), and elongation (<span><math><mrow><msub><mi>ε</mi><mtext>EL</mtext></msub></mrow></math></span>). The present work examines models, identifies outliers, and provides insights into mechanical properties, for example, (i) <span><math><mrow><msub><mi>H</mi><mi>B</mi></msub></mrow></math></span> is correlated by <span><math><mrow><msub><mi>Q</mi><mi>V</mi></msub></mrow></math></span>, <span><math><mrow><msub><mi>σ</mi><mtext>UT</mtext></msub></mrow></math></span> by <span><math><mrow><msqrt><msub><mi>γ</mi><mi>s</mi></msub></msqrt></mrow></math></span> or <span><math><mrow><msqrt><msub><mi>γ</mi><mtext>us</mtext></msub></msqrt></mrow></math></span>, and <span><math><mrow><msub><mi>K</mi><mtext>Ic</mtext></msub></mrow></math></span> by <span><math><mrow><msub><mi>γ</mi><mi>s</mi></msub></mrow></math></span>; (ii) data outliers are identified for Cr (related to <span><math><mrow><msub><mi>τ</mi><mtext>is</mtext></msub></mrow></math></span>, <span><math><mrow><msub><mi>γ</mi><mi>s</mi></msub></mrow></math></span>, <span><math><mrow><msub><mi>Q</mi><mi>V</mi></msub></mrow></math></span>, and <span><math><mrow><msub><mi>σ</mi><mtext>UT</mtext></msub></mrow></math></span>), Be (<span><math><mrow><msub><mi>τ</mi><mtext>is</mtext></msub></mrow></math></span>, <span><math><mrow><msub><mi>γ</mi><mtext>sf</mtext></msub></mrow></math></span>, <span><math><mrow><msub><mi>γ</mi><mtext>us</mtext></msub></mrow></math></span>, and <span><math><mrow><msub><mi>Q</mi><mi>V</mi></msub></mrow

尽管机械特性对特定材料的适用性和寿命起着至关重要的作用，但从根本上揭示机械特性的工作远未完成。在此，我们通过基于密度泛函理论（DFT）的计算，对 60 种 bcc、fcc、hcp 和/或金刚石结构的纯元素的机械特性进行了全面研究，并对现有文献进行了广泛回顾。本数据汇编可对机械性能进行详细的关联分析，重点关注基于 DFT 的理想剪切和拉伸强度（τis 和 σit）、稳定和不稳定堆积断层能（γsf 和 γus）、表面能（γs）和空位活化能（QV）；以及实验硬度（HB）、极限拉伸强度（σUT）、断裂韧性（KIc）和伸长率（εEL）。本研究对模型进行了检验，确定了异常值，并提供了对机械性能的见解，例如：(i) HB 与 QV 相关，σUT 与 γs 或 γus 相关，KIc 与 γs 相关；(ii) 找出以下方面的数据异常值：铬（与 τis 、γs 、QV 和 σUT 有关）、铍（τis 、γsf 、γus 和 QV ）、铪（HB 和 KIc ）、镱（所有性质）和铂（γsf 与 γus 的关系）；以及 iii.γus）；(iii) τis、σit、γsf、γus、γs、QV 和 HB 与元素属性高度相关，而 σUT、KIc，特别是 εEL 则主要由于实验不确定性而相关性较低。特别是，目前的数据汇编为多组分合金的 γs 和 τis 以及 bcc Ti、Zr 和 Hf 等不稳定结构的 τis 等属性建模提供了坚实的基础。

引用次数: 0

Interaction of propagating crack with microstructure in CGI: In situ tensile test and numerical simulation CGI 中扩展裂纹与微观结构的相互作用：原位拉伸试验和数值模拟

IF 6.1 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2024-10-24 DOI: 10.1016/j.msea.2024.147431

Xingling Luo , Xinrui Huang , Konstantinos P. Baxevanakis , Phani S. Karamched , Vadim V. Silberschmidt

Compacted graphite iron (CGI) is a double-phase material, in which complex graphite morphology greatly influences crack initiation and propagation. Despite its wide use and considerable past research on the fracture behaviour of CGI, the understanding of the interaction of propagating cracks with CGI's microstructure is still limited. In this study, a novel method is employed that integrates scanning electron microscopy (SEM) and an optical high-speed camera. This approach allows the clear visualisation of microstructures before and after fracture, as well as the calculation of crack-propagation rate during tensile tests. It is also revealed for the first time that in the case of graphite particles situated at a specific distance from the primary crack path, the initiation of secondary micro-cracks, near particles does not occur. A critical distance from the main crack path for crack initiation is analysed. Further, finite-element simulations are developed to study the effect of microstructure on the fracture behaviour of the tested microstructures. A Johnson-Cook (JC) damage model is calibrated and used in all simulations. The crack path and velocity of simulation results are in good agreement with the experimental data, demonstrating that the JC damage model can be used to predict the crack initiation and propagation of CGI. It is found that interface debonding and crack initiation always tend to appear near the tip of vermicular graphite. Thus, large vermicular graphite particles can affect negatively the toughness of CGI. Graphite particles situated farther from the primary crack significantly reduce the likelihood of crack initiation in that specific location. Furthermore, large nodular graphite particles absorb energy and generate secondary cracks, while small graphite particles have little effect on the crack-path direction. The newly discovered fracture mechanisms and simulation results provide new insights for the design and manufacture of metal-matrix composites (e.g., Al/SiC) with optimal mechanical properties.

压实石墨铁（CGI）是一种双相材料，其中复杂的石墨形态对裂纹的产生和扩展有很大影响。尽管这种材料被广泛使用，而且过去对其断裂行为进行了大量研究，但人们对裂纹扩展与石墨铸铁微观结构之间相互作用的了解仍然有限。本研究采用了一种新方法，将扫描电子显微镜（SEM）和光学高速相机结合在一起。通过这种方法，可以清晰地观察到断裂前后的微观结构，并计算出拉伸试验过程中的裂纹扩展速率。研究还首次发现，在石墨颗粒与主裂纹路径保持一定距离的情况下，颗粒附近不会出现次生微裂纹。分析了裂纹萌生的主裂纹路径临界距离。此外，还进行了有限元模拟，以研究微结构对测试微结构断裂行为的影响。所有模拟都校准并使用了约翰逊-库克（JC）损伤模型。模拟结果的裂纹路径和速度与实验数据十分吻合，表明 JC 损伤模型可用于预测 CGI 的裂纹起始和扩展。研究发现，界面脱粘和裂纹起始总是倾向于出现在蠕墨尖端附近。因此，大的蠕墨颗粒会对 CGI 的韧性产生负面影响。距离主裂纹较远的石墨颗粒会大大降低在该特定位置出现裂纹的可能性。此外，大的结核石墨颗粒会吸收能量并产生次生裂纹，而小的石墨颗粒对裂纹路径方向的影响很小。新发现的断裂机制和模拟结果为设计和制造具有最佳机械性能的金属基复合材料（如 Al/SiC）提供了新的思路。

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引用次数: 0

Quantitative characterization of local deformation-fracture behavior in ferrite-martensite dual-phase steels with different martensite distributions 不同马氏体分布的铁素体-马氏体双相钢局部变形-断裂行为的定量表征

IF 6.1 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2024-10-24 DOI: 10.1016/j.msea.2024.147445

Myeong-heom Park , Ryota Matsubayashi , Akinobu Shibata , Nobuhiro Tsuji

Low-carbon dual-phase (DP) steels, composed of a soft ferrite phase and a hard martensite phase, are known as promising advanced high-strength steels (AHSSs) due to their high strength and good ductility at low fabrication cost. However, the deformation behavior of DP steels is still not fully understood because of their complex mixed-phase distribution and mechanical interactions between two phases during deformation. The present study quantitatively investigated the effect of martensite distribution on mechanical properties and local deformation-fracture behavior, using the digital image correlation (DIC) technique. Two types of DP structures were prepared: one with a chained martensite distribution (chained DP) and one with an isolated martensite distribution (isolated DP). The chained DP specimen exhibited a superior tensile property, achieving both high strength and large ductility compared to the isolated DP specimen. DIC strain analysis revealed that the chained DP structure showed relatively homogeneous deformation due to the greater contribution of martensite to plastic deformation. In contrast, the isolated DP specimen experienced significant strain localization in the soft ferrite grains. Despite high global strains, non-plastically deformed zones were observed in the central regions of large, isolated martensite particles. Notable differences in micro-void evolution were also observed between the two specimens. The chained DP specimen had a large number of randomly distributed micro-voids, ranging from 0.5 μm to 2 μm in size. In contrast, the isolated DP specimen contained fewer micro-voids, with some aligned at an angle of ∼65° to the tensile direction, potentially leading to early tensile fracture.

由软铁素体相和硬马氏体相组成的低碳双相钢（DP）具有强度高、延展性好、制造成本低的特点，是一种很有前途的先进高强度钢（AHSS）。然而，由于 DP 钢复杂的混相分布以及变形过程中两相之间的机械相互作用，人们对其变形行为仍不完全了解。本研究采用数字图像相关（DIC）技术，定量研究了马氏体分布对力学性能和局部变形-断裂行为的影响。研究人员制备了两种 DP 结构：一种是链状马氏体分布（链状 DP），另一种是孤立马氏体分布（孤立 DP）。与孤立 DP 试样相比，链状 DP 试样具有更优越的拉伸性能，既能获得较高的强度，又能获得较大的延展性。DIC 应变分析表明，由于马氏体对塑性变形的贡献较大，链状 DP 结构显示出相对均匀的变形。相比之下，孤立的 DP 试样在软铁素体晶粒中出现了明显的应变局部化。尽管整体应变很高，但在大的孤立马氏体颗粒的中心区域观察到了非塑性变形区。两种试样在微空洞演变方面也存在显著差异。链状 DP 试样有大量随机分布的微空洞，大小从 0.5 μm 到 2 μm 不等。相比之下，孤立 DP 试样中的微空洞数量较少，其中一些与拉伸方向成 65° 夹角，可能导致早期拉伸断裂。

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引用次数: 0