Journal of Alloys and Metallurgical Systems最新文献_第10页

Study of phase evolution and phase stability in a novel FCC based Al30Ti35Mg5V10Fe8Cr12 lightweight high-entropy alloy processed by mechanical alloying 机械合金化制备新型FCC基Al30Ti35Mg5V10Fe8Cr12轻量化高熵合金的相演化与相稳定性研究

Journal of Alloys and Metallurgical Systems

Pub Date : 2025-03-01 Epub Date: 2024-12-09 DOI: 10.1016/j.jalmes.2024.100142

Ayush Sourav , Ankit Singh Negi , Pranjal Chauhan , T. Sudeep Kumar , Shanmugasundaram Thangaraju

High-entropy alloys (HEAs) have gained significant attention from researchers due to their exceptional mechanical properties. While most the reported lightweight high-entropy alloys have Body Centered Cubic (BCC), Hexagonal Close Packed (HCP), and complex intermetallic phases, there is growing interest in development of Face Centered Cubic (FCC) based Lightweight High-Entropy Alloys (LWHEA) for applications prioritizing energy efficiency. In this study, a design strategy for synthesizing a stable FCC-based LWHEA through multivariate optimization of elements and thermodynamic parameters was presented. A novel Al₃₀Ti₃₅Mg₅V₁₀Fe₈Cr₁₂ LWHEA was designed and processed through a mechanical alloying route with a theoretical density of 4.5 g/cc. The compaction of the alloy was performed by spark plasma sintering (SPS) at 890 ℃ and 60 MPa for 15 minutes. The hardness of sintered sample was found to be 550 ± 18 HV (5.3 GPa). Microstructural evolution of the alloy was studied using X-ray diffraction (XRD) and Scanning electron microscopy (SEM). The microstructural analysis of alloy revealed that a combination of FCC and BCC phases are present in milled sample as well as sintered sample. The phase stability was explained through Gibbs free energy calculations of competing phases.

高熵合金以其优异的力学性能受到了研究人员的广泛关注。虽然大多数报道的轻量化高熵合金具有体心立方（BCC），六边形紧密堆积（HCP）和复杂的金属间相，但人们对基于面心立方（FCC）的轻量化高熵合金（LWHEA）的开发越来越感兴趣，以优先考虑能效的应用。本研究提出了一种通过元素和热力学参数的多元优化来合成稳定的基于fcc的LWHEA的设计策略。设计了一种理论密度为4.5 g/cc的新型Al30Ti35Mg5V10Fe8Cr12 LWHEA，并采用机械合金化工艺进行了加工。采用放电等离子烧结（SPS）技术，在890℃、60 MPa、15 min条件下对合金进行压实。烧结试样的硬度为550 ± 18 HV（5.3 GPa）。采用x射线衍射（XRD）和扫描电镜（SEM）研究了合金的微观组织演变。合金的显微组织分析表明，铣削试样和烧结试样均存在FCC相和BCC相的结合。通过竞争相的吉布斯自由能计算解释了相的稳定性。

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引用次数: 0

Surface characteristics optimization and investigation of dual-channel micro electrical discharge drilling on IN617 super alloy IN617高温合金双通道微放电钻孔表面特性优化及研究

Journal of Alloys and Metallurgical Systems

Pub Date : 2025-03-01 Epub Date: 2025-02-27 DOI: 10.1016/j.jalmes.2025.100172

Anish Nair , Wojciech Bizoń , Sebastian Skoczypiec , Rafal Bogucki , L. Selvarajan

This article details the experimental investigation on surface roughness, spatter area and white layer thickness in micro electrical discharge machining of IN617 alloy. The alloy here is a high hardness superalloy preferred to be machined by non-conventional techniques. Here we present the micromachining behaviour of the alloy. Micro electrical discharge machining is conducted using a dual channel copper electrode and the surface characteristics are observed. Other than the traditional input factors, retraction duration of the electrode is also focussed here. White layer characteristics at different heights of the drilled hole are measured and characterized. Intensive microscopic images have been presented to detail the behaviour of the process. The behaviour of individual responses towards the various input factors has been illustrated. A multiobjective optimization model is also developed to extract the best parametric combinations at which optimal surface characteristics can be obtained.The major factor affecting the spatter area and white layer thickness is Pulse on time. The increase in pulse on time creates a high frequency of sparks which leads to rapid metal erosion at the vicinity of the electrode. In the case of surface roughness, the current was observed as the most dominant factor which corresponds to earlier studies on similar processes. Detailed microstructural analysis depicting heat affected zone, white layer thickness and surface deformities have been reported to understand the mechanism of the process.

本文详细介绍了微放电加工 IN617 合金时表面粗糙度、飞溅面积和白层厚度的实验研究。该合金是一种高硬度超级合金，适合采用非常规技术进行加工。我们在此介绍该合金的微加工性能。我们使用双通道铜电极进行微放电加工，并观察其表面特征。除了传统的输入因素外，电极的回缩时间也是重点。对钻孔不同高度的白层特征进行了测量和表征。此外，还提供了大量显微图像，以详细说明加工过程的行为。还说明了对各种输入因素的个别反应行为。此外，还开发了一个多目标优化模型，以提取可获得最佳表面特征的最佳参数组合。脉冲接通时间的增加会产生高频率的火花，从而导致电极附近的金属快速侵蚀。在表面粗糙度方面，观察到电流是最主要的因素，这与之前对类似工艺的研究一致。详细的微观结构分析描绘了热影响区、白层厚度和表面变形，以了解该过程的机理。

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引用次数: 0

Metallurgical and mechanical properties of failed railway screw coupling in screw part 失效铁路螺纹联轴器螺纹件的冶金和力学性能

Journal of Alloys and Metallurgical Systems

Pub Date : 2025-03-01 Epub Date: 2025-01-27 DOI: 10.1016/j.jalmes.2025.100157

Sabry.M. Abdel Aziz , F. Abdel Mouez , M.A. Morsy

Metallurgical and mechanical investigations were applied to investigate the failure of the screw in train screw coupling. The results showed that the steel of the screw parts is DIN 41Cr4 steel with ferrite-pearlite microstructure. This indicates that the steel did not have the proper heat treatment according to the UIC code (826, 3rd edition, 2004), which is hardening and tempering to give the best mechanical properties especially fatigue resistance. Moreover, SEM micrographs show that the initiation point of crack is at the sharp points of the thread root, these sharp points act as a stress raiser that initiates the crack and accelerates the fatigue failure. Proper hardening and tempering process was conducted; this gave tempered martensite microstructure with acceptable mechanical properties that agreed with UIC code 826. The tempered martensite structure has a high fatigue resistance than the ferrite-pearlite structure. Therefore, it is highly recommended to form the threads by rolling dies instead of machining. This will result in the formation of rounded thread roots instead of sharp thread roots. The rounded thread roots are expected to improve the fatigue resistance especially when it is always done after heat treatment processes.

采用冶金学和力学方法对列车螺纹联轴器中螺纹的失效进行了研究。结果表明：螺杆件的材质为din41cr4钢，具有铁素体-珠光体组织；这表明该钢没有按照UIC规范（826，第3版，2004）进行适当的热处理，即淬火和回火，以获得最佳的机械性能，特别是抗疲劳性能。扫描电镜分析表明，裂纹的起裂点位于螺纹根部的尖点处，这些尖点作为应力源，起起裂纹的起裂作用，加速了疲劳破坏。进行适当的调质工艺；这使得回火马氏体组织具有可接受的力学性能，符合UIC规范826。回火马氏体组织比铁素体-珠光体组织具有更高的抗疲劳性能。因此，强烈建议用滚模而不是机械加工来形成螺纹。这将导致形成圆形的螺纹根，而不是锋利的螺纹根。特别是在热处理工艺之后，圆螺纹根有望提高抗疲劳性。

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引用次数: 0

Impact of friction stir welding on the mechanical and microstructural properties of austempered ductile iron and mild steel joints 搅拌摩擦焊对等温球墨铸铁与低碳钢接头力学性能和组织性能的影响

Journal of Alloys and Metallurgical Systems

Pub Date : 2025-03-01 Epub Date: 2025-01-15 DOI: 10.1016/j.jalmes.2025.100154

M.S. Hussein , Ebtesam E. Ateia , A. Nofal , M.A. Morsy

This study investigates the dissimilar welding of Austempered Ductile Iron (ADI) with mild steel by using friction stir welding (FSW). Both materials are widely utilized in many fields owing to the exceptional properties and relatively competitive costs. However, joining two materials with different chemical and mechanical properties presents significant challenges. After many modifications in FSW parameters, a successful butt-joint was achieved by fixing the ADI in the retreating side (RS) and mild steel in the advancing side (AS), using rotational speed 800 RPM and travelling speed 50 mm/min. These parameters have resulted a well-formed stir zone (SZ) and thermo-mechanical affected zone (TMAZ) without grooves or cracks. The microstructure of the weld regions exhibited deformation of graphite nodules into strips and mainly martensitic structure at SZ, but no carbide phases or cracks were observed in the SZ. The analysis of the as-welded samples showed that the maximum microhardness values are 590 HV and 406 HV at the SZ and TMAZ respectively, and the tensile strength is 350 MPa when fractured at AS-TMAZ. Post-weld tempering at 370°C for 1 hour has resulted a formation of tempered martensite at the SZ, and an obvious reduction in the microhardness values to 395 HV at SZ and 350 HV at TMAZ. The tensile strength has slightly improved and fractured at the mild steel base metal. These results demonstrate a successful joining of ADI and mild steel using FSW.

研究了等温球墨铸铁（ADI）与低碳钢的搅拌摩擦焊异种焊接。由于优异的性能和相对具有竞争力的成本，这两种材料被广泛应用于许多领域。然而，连接两种具有不同化学和机械性能的材料提出了重大挑战。在对FSW参数进行多次修改后，通过将ADI固定在后退侧（RS），将低碳钢固定在前进侧（AS），转速为800 RPM，移动速度为50 mm/min，成功实现了对接。这些参数导致搅拌区（SZ）和热机械影响区（TMAZ）形成良好，没有沟槽或裂纹。焊接区组织表现为石墨结核条状变形，焊接区以马氏体组织为主，焊接区未见碳化物相和裂纹。焊接态试样的分析结果表明，焊接态试样在SZ和TMAZ处的显微硬度最大值分别为590 HV和406 HV，在AS-TMAZ处断裂时的抗拉强度为350 MPa。焊后在370°C下回火1 小时，在SZ处形成回火马氏体，显微硬度值在SZ处明显降低到395 HV，在TMAZ处降低到350 HV。拉伸强度略有提高，在低碳钢母材处断裂。这些结果表明，使用FSW成功地连接了ADI和低碳钢。

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引用次数: 0

Role of metallic carbides on high temperature mechanical properties of wire arc additive manufactured GH4099 Ni-based superalloy 金属碳化物对丝弧添加剂制备GH4099镍基高温合金高温力学性能的影响

Journal of Alloys and Metallurgical Systems

Pub Date : 2025-03-01 Epub Date: 2025-02-10 DOI: 10.1016/j.jalmes.2025.100163

Wei Pan , Bin Xu , Chenxi Liu

Wire arc additive manufactured (WAAMed) γ′-strengthened Ni-based superalloy always suffers from the undesired and excessive carbides, due to the rapid cooling rates, resulting the degradation of the alloy's mechanical properties. To solve this issue, GH4099 γ′-strengthened Ni-based superalloy was prepared by melt inert-gas welding additive manufacturing, followed by both high and low temperature post-heat treatments. Both high density larger MC and tiny-dispersive M₂₃C₆ carbides were observed at the subgrain boundary in the as-built alloy, causing a higher strength but normal ductility due to the micro-cracks at the MC carbide/matrix interface. 1200 °C 4 h heat treatment, induced the growth of the large MC carbide and dissolved M₂₃C₆ carbides, resulting the improvement of the ductility of the alloy by scarifying the strength. 900 °C 4 h treatment has limited effects on the carbides’ morphology and sizes, but 900 °C 50 h treatment caused the dissolving of the large MC carbide and the growing of the tiny M₂₃C₆ carbide. Such carbide evolution can not only introduce more strengthening phase, but also suppressing the crack initiation at the large carbide/matrix interface, which simultaneously improve the strength and the ductility of the as-built alloy.

焊丝电弧添加剂制造（WAAMed）的γ′强化镍基高温合金由于冷却速度快，总是存在多余的碳化物，导致合金的力学性能下降。为了解决这一问题，采用熔体惰性气焊增材制造工艺制备了GH4099 γ′强化镍基高温合金，并进行了高温和低温后热处理。在亚晶界处观察到高密度的大MC和微弥散的M23C6碳化物，由于MC碳化物/基体界面处存在微裂纹，导致合金强度较高，但塑性正常。1200°C 4 h热处理，诱导大MC碳化物的生长和M23C6碳化物的溶解，通过降低强度提高合金的塑性。900°C 4 h处理对碳化物的形貌和尺寸影响有限，但900°C 50 h处理导致大型MC碳化物的溶解和微小M23C6碳化物的生长。这种碳化物的析出不仅可以引入更多的强化相，还可以抑制大碳化物/基体界面处的裂纹萌生，从而提高合金的强度和塑性。

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引用次数: 0

Prediction of mechanical properties and defect detection in a TIG cladded SS 316 L by machine learning techniques 用机器学习技术预测TIG涂层SS 316 L的力学性能和缺陷检测

Journal of Alloys and Metallurgical Systems

Pub Date : 2025-03-01 Epub Date: 2025-02-19 DOI: 10.1016/j.jalmes.2025.100167

Shanmuga Vadivu K R , Varun Kumar A , Sathickbasha K

Machine learning techniques are being widely adopted across the globe for their reliability and flexibility when compared with other traditional methods. However, the selection of suitable machine learning techniques has a major role in a process for the prediction of optimal process parameters. In this study, we have adopted two different machine learning techniques Adaptive Neuro-Fuzzy Inference System (ANFIS) and Unified Convolutional Neural Network (UCNN) for the identification of optimal process parameters for the SS 316 L base alloy cladded with Er-NiCr-3 filler by Tungsten Inert Gas (TIG) cladding process. The ANFIS methodology will develop a model with a range of process parameters that can be used to determine the theoretical values, whereas the UCNN uses images for the identification of any defect in the samples the images are broken as different pixels based on the algorithms employed. Here, we have correlated the machine learning outputs with the actual experimental values (microhardness and tensile values are considered for the correlation). Whereas, for the UCNN technique we have procured the grain structures of the cladded samples. It is inferred from the comparison that the machine learning technique had shown sound and reliable outputs with an error percentage (≈ 0.1–2.0 %) in line with the actual data. Therefore from the study, it is revealed that the adoption of machine learning techniques can be utilized wisely for a process in the prediction of optimal process parameters in a flexible manner when compared with the other traditional optimization techniques.

与其他传统方法相比，机器学习技术具有可靠性和灵活性，因此在全球范围内被广泛采用。然而，选择合适的机器学习技术在预测最佳工艺参数的过程中起着重要作用。在本研究中，我们采用了两种不同的机器学习技术：自适应神经模糊推理系统（ANFIS）和统一卷积神经网络（UCNN），用于识别通过钨惰性气体（TIG）熔覆工艺熔覆 Er-NiCr-3 填充物的 SS 316 L 基合金的最佳工艺参数。ANFIS 方法将建立一个包含一系列工艺参数的模型，可用于确定理论值，而 UCNN 则使用图像来识别样品中的任何缺陷，根据所采用的算法，图像被分割为不同的像素。在这里，我们将机器学习的输出结果与实际实验值（显微硬度和拉伸值）进行了关联。而在 UCNN 技术中，我们获得了粘合样品的晶粒结构。从比较中可以推断出，机器学习技术的输出结果可靠，误差率（≈ 0.1-2.0%）与实际数据相符。因此，研究表明，与其他传统优化技术相比，采用机器学习技术可以灵活地预测最佳工艺参数。

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引用次数: 0

Metallurgical assessment of Al-Zr-Y alloys for laser-based processing 激光加工Al-Zr-Y合金的冶金性能评价

Journal of Alloys and Metallurgical Systems

Pub Date : 2025-03-01 Epub Date: 2025-02-03 DOI: 10.1016/j.jalmes.2025.100159

J.T. Hierlihy , I.W. Donaldson , D.P. Bishop

The scope of aluminum alloys commercially available for laser-based additive manufacturing is limited yet the demand for them is growing aggressively. In many cases, end-users are particularly interested in those that offer enhanced thermal stability. Historically, several such materials were premised on alloys that incorporated transition metal (TM) additions which formed refractory aluminides as the principal strengthening addition. The objective of this study was to pursue a similar concept but as applied to the ternary Al-Zr-Y alloy system. In doing so, plates with varying Zr and Y contents (0–2 wt%) were cast and subsequently subjected to laser remelting (LRM) using a Yb-fibre laser. Microstructures then characterized using laser confocal microscopy, XRD, SEM, and TEM. LRM was seen to produce an epitaxial columnar α-Al matrix in binary Al-Y alloys, with intergranular solidification cracking seen in the highest Y content of 2 wt%. In Al-Zr specimens, increasing Zr content resulted in the development of a duplex microstructure consisting of distinct epitaxial columnar regions near the melt pool boundary and equiaxed regions near the center. The development of equiaxed regions was ascribed to the presence of sub-micron dispersoids. These dispersoids were Zr-rich and increased in number with corresponding increases in Zr content. They were also observed in Al-Zr-Y specimens and were subsequently identified as an L1₂-Al₃Zr. The addition of Y produced a dramatic increase in dispersoid density, and consequently the proportion of equiaxed grains, demonstrating that the Al-Zr-Y system is a promising candidate for laser-based processing technologies.

可用于激光增材制造的铝合金的商业范围是有限的，但对它们的需求正在积极增长。在许多情况下，终端用户对那些提供增强热稳定性的产品特别感兴趣。从历史上看，一些这样的材料是以加入过渡金属（TM）的合金为前提的，这些过渡金属（TM）形成难熔铝化物作为主要的强化添加剂。本研究的目的是追求类似的概念，但适用于三元Al-Zr-Y合金系统。在此过程中，铸造具有不同Zr和Y含量（0-2 wt%）的板，随后使用yb光纤激光器进行激光重熔（LRM）。然后用激光共聚焦显微镜、XRD、SEM和TEM对其微观结构进行了表征。在二元Al-Y合金中，LRM形成了外延柱状α-Al基体，在Y含量最高为2 wt%时出现了晶间凝固开裂。在Al-Zr试样中，随着Zr含量的增加，熔池边界附近的外延柱状区和中心附近的等轴区形成了双相组织。等轴区的发育归因于亚微米分散体的存在。这些分散体富含Zr，且随着Zr含量的增加，分散体的数量也相应增加。它们也在Al-Zr-Y样品中观察到，随后被鉴定为L12-Al3Zr。Y的加入大大增加了分散体密度，从而增加了等轴晶粒的比例，这表明Al-Zr-Y体系是激光加工技术的一个有前途的候选者。

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引用次数: 0

Effect of heat treatment on phase transformation behavior, tensile fracture mechanism and spring application characteristics of 631 stainless steel 热处理对 631 不锈钢相变行为、拉伸断裂机制和弹簧应用特性的影响

Journal of Alloys and Metallurgical Systems

Pub Date : 2024-12-01 Epub Date: 2024-10-25 DOI: 10.1016/j.jalmes.2024.100119

Chien-Te Huang , Fei-Yi Hung , Jun-Ren Zhao , Bo-Ding Wu , Ho-Yen Hsieh

This study focuses on enhancing the mechanical properties of 631 stainless steel through heat treatment for spring applications. 631 stainless steel (17–7PH), can achieve increased hardness and mechanical properties, offering high strength and hardness suitable for use in aerospace, chemical, and automotive industries. Heat treatment was recommended as one of the best ways in this regard; hence, the effects of temperature and time on the microstructure, mechanical, and corrosion properties of 631 stainless steel have been studied. This research conducted a series of heat treatments on 631 stainless steel, included solid-solution treatment, CH900, RH950, and TH1050 processes to modify the temperature holding period and the degree of undercooling of phase transformations. The study explored the microstructure and mechanical properties of each heat treatment, including spring tests. The results indicate that solid-solution treatment has no significant contribution to hot-rolled 631 stainless steel, whereas two-stage aging is able to conspicuously improves material hardness and mechanical performance. Quenching in 0°C ice water (increasing the degree of undercooling) can elevate hardness to approximately HRC40. After a two-stage aging heat treatment, 631 stainless steel possesses excellent strength and corrosion resistance. Spring test results show a K value of 1.1 kg/ mm, indicating its potential application.

本研究的重点是通过热处理提高 631 不锈钢在弹簧应用中的机械性能。631 不锈钢（17-7PH）可提高硬度和机械性能，提供适合航空航天、化工和汽车行业使用的高强度和高硬度。热处理被推荐为这方面的最佳方法之一；因此，研究人员对温度和时间对 631 不锈钢的微观结构、机械和腐蚀特性的影响进行了研究。本研究对 631 不锈钢进行了一系列热处理，包括固溶处理、CH900、RH950 和 TH1050 工艺，以改变相变的保温期和过冷度。研究探讨了每种热处理的微观结构和机械性能，包括弹簧试验。结果表明，固溶处理对热轧 631 不锈钢没有明显作用，而两阶段时效则能明显改善材料硬度和机械性能。在 0°C 冰水中淬火（增加过冷度）可将硬度提高到约 HRC40。经过两阶段时效热处理后，631 不锈钢具有出色的强度和耐腐蚀性。弹簧测试结果表明，其 K 值为 1.1 kg/mm，这表明它具有潜在的应用价值。

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引用次数: 0

Effect of minor addition of silicon on deformation behaviour and texture evolution in CrFeNi medium entropy alloy 少量添加硅对CrFeNi中熵合金变形行为和织构演化的影响

Journal of Alloys and Metallurgical Systems

Pub Date : 2024-12-01 Epub Date: 2024-11-26 DOI: 10.1016/j.jalmes.2024.100133

Swati Mahato , Tirupati Dhidhi , Nilesh P. Gurao , Krishanu Biswas

The present investigation systematically explores the effect of a minor addition of silicon on the microstructure, texture, and mechanical properties of FCC CrFeNi medium entropy alloy during rolling at room temperature. The addition of 2 at% Si in CrFeNi alloy results in the reduction of stacking fault energy from 22.4 mJ/m² for CrFeNi to 18.6 mJ/m² for (CrFeNi)₉₈Si₂ alloy. Bulk texture analysis reveals the presence of Brass and Goss texture components in the 90 % rolled samples. Microtextural study reveals that in CrFeNi and (CrFeNi)₉₈Si₂ alloy, Goss-orientated grains exhibit greater stability throughout the deformation compared to Cu-oriented grains. In addition to twinning, profuse shear banding was observed in both alloys at 90 % rolling reduction. The mechanical properties of homogenised (CrFeNi)₉₈Si₂ alloy demonstrate the enhanced combination of yield strength and hardness due to improved solid solution strengthening and dislocation strengthening accompanied by a marginal decrease in ductility due to twinning-induced strain hardening. While in 90 % rolled CrFeNi and (CrFeNi)₉₈Si₂ alloy, both yield strength and ultimate tensile strength increase drastically due to enhanced solid solution and dislocation strengthening though with a significant decrease in ductility.

本研究系统地探讨了少量添加硅对FCC CrFeNi中熵合金室温轧制过程中组织、织构和力学性能的影响。（CrFeNi）98Si2合金的层错能从（CrFeNi）的22.4 mJ/m2降低到（CrFeNi）的18.6 mJ/m2。整体织构分析表明，在90% %的轧制样品中存在黄铜和高斯织构成分。显微组织研究表明，在CrFeNi和（CrFeNi）98Si2合金中，goss取向晶粒在整个变形过程中表现出比cu取向晶粒更大的稳定性。除了孪晶外，两种合金在90% %轧制压下均出现大量剪切带。均匀化（CrFeNi）98Si2合金的力学性能表现为屈服强度和硬度的提高，这是由于固溶强化和位错强化的改善，同时由于孪晶引起的应变硬化，塑性略有下降。而在90% %轧制的CrFeNi和（CrFeNi）98Si2合金中，屈服强度和极限抗拉强度由于固溶和位错强化的增强而显著提高，但塑性显著降低。

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引用次数: 0

Grain size dependent deformation microstructure evolution and work-hardening in CoCrNi medium entropy alloy 钴铬镍中熵合金中与晶粒尺寸相关的变形微结构演化和加工硬化

Journal of Alloys and Metallurgical Systems

Pub Date : 2024-12-01 Epub Date: 2024-11-03 DOI: 10.1016/j.jalmes.2024.100123

Shuhei Yoshida , Genki Yamashita , Takuto Ikeuchi , Yu Bai , Akinobu Shibata , Nobuhiro Tsuji

This study clarified the grain size dependence of the deformation microstructure evolution and work-hardening behavior in CoCrNi medium entropy alloy. We fabricated fully recrystallized specimens with coarse-grained (CG) and ultrafine-grained (UFG) specimens by severe plastic deformation and subsequent annealing processes. Tensile deformation was applied to the specimens at room temperature. The UFG specimen exhibited both high strength and high ductility compared to conventional UFG metals due to the high work-hardening ability. In the CG specimen, three distinct types of deformation microstructures consisting of dislocations and deformation twins developed depending on grain orientations, similar to the single-crystalline specimens. In the UFG specimen, widely-extended stacking faults and randomly-tangled dislocations were found to coexist in most grains. Deformation twins were found to nucleate without evidence of dislocation reactions regardless of grain orientations, implying abnormal nucleation mechanisms of deformation twins in the UFG specimen. Dislocation densities quantified by in-situ synchrotron XRD measurements during tensile deformation were higher in the UFG specimen than those in the CG specimen and conventional UFG metals. Our analysis showed that the work-hardening behavior of the specimens was primarily controlled by increases in dislocation density as well as the introduction of planar defects during deformation. Through comparisons with the CG specimen and conventional UFG metals, we concluded that the excellent work-hardening ability of the UFG specimen was mainly due to the evolution of unique deformation microstructures and rapid increase in dislocation density, which could be due to inhibited dynamic recovery in the MEA.

本研究阐明了钴铬镍中熵合金变形微观组织演变和加工硬化行为的晶粒尺寸依赖性。我们通过剧烈塑性变形和随后的退火过程，制作了具有粗晶粒（CG）和超细晶粒（UFG）的完全再结晶试样。试样在室温下进行拉伸变形。与传统的超细晶粒金属相比，超细晶粒试样由于具有较高的加工硬化能力，因此表现出高强度和高延展性。在 CG 试样中，根据晶粒取向的不同，由位错和变形孪晶组成的三种不同类型的变形微观结构得到了发展，这与单晶试样类似。在 UFG 试样中，发现大多数晶粒中同时存在广泛延伸的堆积断层和随机纠缠的位错。在 UFG 试样中，无论晶粒取向如何，变形孪晶的成核过程都没有位错反应的迹象，这意味着变形孪晶的成核机制异常。在拉伸变形过程中，通过原位同步辐射 XRD 测量量化的位错密度在 UFG 试样中高于 CG 试样和传统 UFG 金属。我们的分析表明，试样的加工硬化行为主要受控于位错密度的增加以及变形过程中平面缺陷的引入。通过与 CG 试样和传统 UFG 金属的比较，我们得出结论：UFG 试样之所以具有出色的加工硬化能力，主要是由于其独特的变形微观结构的演变和位错密度的快速增加，而这可能是由于 MEA 中的动态恢复受到了抑制。

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引用次数: 0