Journal of Materials Processing Technology最新文献_第2页

Continuous and discontinuous dynamic recrystallization in the superplastic deformation of moderately cold-deformed Cr4Mo4Ni4V martensitic steel 中度冷变形 Cr4Mo4Ni4V 马氏体钢超塑性变形中的连续和不连续动态再结晶

IF 6.7 2区材料科学 Q1 ENGINEERING, INDUSTRIAL

Journal of Materials Processing Technology

Pub Date : 2024-10-29 DOI: 10.1016/j.jmatprotec.2024.118647

Wanli Yang , Hongwei Jiang , Pengwen Zhou , Bin Shao , Yingying Zong

This study employs lath martensite as the starting structure to achieve superplasticity through limited cold deformation, revealing how the dynamic recrystallization mechanism during superplastic deformation changes with the amount of prior cold deformation. Results show that an elongation close to 700 % can be achieved with 25 % cold deformation, and the peak stress is significantly reduced. The amount of deformation required to achieve superplasticity with martensite as the initial processing structure is much lower than with ferrite as the initial processing structure. However, when the deformation increased from 25 % to 50 %, the elongation increased only slightly, from 696 % to 756 %, while the peak stress increased from 90.1 MPa to 96.4 MPa. The reason is that continuous dynamic recrystallization (CDRX) is suppressed, and softening occurs only through discontinuous recrystallization (DDRX), thus weakening the softening effect. The superplastic deformation mechanism for samples with high cold deformation mainly involves grain boundary sliding (GBS) associated with DDRX, while for samples with moderate cold deformation, it involves GBS accompanied by both CDRX and DDRX. Strain rate jump (SRJ) tests reveal that even 5 % cold deformation can accelerate the growth of the m-value during deformation. Interestingly, the m-value of the 25 % deformed sample is slightly higher than that of the 50 % deformed sample. This research offers a promising route for achieving superplasticity in high-alloy low-carbon steel, revealing continuous and discontinuous dynamic recrystallization accompanied by grain boundary sliding in superplastic cold-deformed martensitic Cr₄Mo₄Ni₄V steel.

本研究采用板条马氏体作为起始结构，通过有限的冷变形实现超塑性，揭示了超塑性变形过程中的动态再结晶机制如何随先前冷变形量的变化而变化。结果表明，25%的冷变形可实现接近700%的伸长率，峰值应力显著降低。以马氏体为初始加工结构时，实现超塑性所需的变形量远低于以铁素体为初始加工结构时的变形量。然而，当变形量从 25 % 增加到 50 % 时，伸长率仅略有增加，从 696 % 增加到 756 %，而峰值应力却从 90.1 兆帕增加到 96.4 兆帕。原因是连续动态再结晶（CDRX）受到抑制，软化仅通过不连续再结晶（DDRX）发生，从而削弱了软化效应。高冷变形样品的超塑性变形机制主要涉及与 DDRX 相关的晶界滑动（GBS），而中等冷变形样品的超塑性变形机制则涉及与 CDRX 和 DDRX 相关的 GBS。应变速率跃变（SRJ）测试表明，即使是 5% 的冷变形也会在变形过程中加速 m 值的增长。有趣的是，25% 变形样品的 m 值略高于 50% 变形样品的 m 值。这项研究揭示了超塑性冷变形马氏体 Cr4Mo4Ni4V 钢中伴随晶界滑动的连续和不连续动态再结晶，为实现高合金低碳钢的超塑性提供了一条可行的途径。

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引用次数: 0

Improving current window in keyhole welding with double-layers hybrid arc heat source 利用双层混合电弧热源改善锁孔焊接的电流窗口

IF 6.7 2区材料科学 Q1 ENGINEERING, INDUSTRIAL

Journal of Materials Processing Technology

Pub Date : 2024-10-28 DOI: 10.1016/j.jmatprotec.2024.118646

ZuMing Liu , BoHan Jia , XuMin Guo , XingChuan Zhao

Keyhole welding can be easily achieved with a plasma arc, but the process window is narrow because too high arc pressure will damage the keyhole stability. Double-layers hybrid arc heat source was developed by compositing an outer layer of free arc into the center plasma arc jet, the arc heat power can be adjusted in wide range with suppression of arc pressure changing. Keyhole stability was tested to be improved with 6mm-thick stainless steel in previous works, but the stability principle is not yet discussed. In this paper, keyhole welding tests were carried out with thicker steel plates to evaluate the usable welding current window improvement and the weld pool stabilization principle. Results show that the usable current window with the hybrid arc is nearly double wider over that with plasma arc in the 6mm-, 8mm- and 16mm-thick plates. The added free arc heat is deposited into the keyhole bottom with limited ratio, the backside weld width increases much more (about 2.4–6 folders) slowly by increasing the free arc current than by increasing the plasma arc current. Keyhole weld pool stabilization principle is outlined: if the plasma arc is given, arc pressure is almost fixed, surface tension in backside weld surface decreases slowly with the free arc current, weld pool force balance can be achieved in much wider range of welding current. Smooth front and backside weld surfaces are easily obtained with hybrid arc. The research indicates that, for application of the developed hybrid arc system in keyhole welding field, the plasma arc should get the fully penetration threshold, the free arc current is used as the process adjuster, the usable welding current range is very wide.

利用等离子弧可以轻松实现锁孔焊接，但由于过高的电弧压力会破坏锁孔的稳定性，因此工艺窗口较窄。双层混合电弧热源是通过在中心等离子弧射流中合成外层自由弧来开发的，电弧热功率可在大范围内调节，并可抑制电弧压力的变化。在以前的工作中，对 6 毫米厚的不锈钢进行了测试，以提高锁孔的稳定性，但尚未讨论其稳定性原理。本文使用更厚的钢板进行了锁孔焊接试验，以评估可用焊接电流窗口的改善情况和焊池稳定原理。结果表明，在 6 毫米、8 毫米和 16 毫米厚的钢板上，混合电弧的可用电流窗口比等离子电弧宽近一倍。增加的自由弧热量以有限的比例沉积到锁孔底部，增加自由弧电流比增加等离子弧电流，背面焊缝宽度的增加速度要慢得多（约 2.4-6 倍）。概述了锁眼焊池稳定原理：如果给定等离子弧，电弧压力几乎固定，背面焊缝表面张力随自由弧电流缓慢减小，焊池力平衡可在更宽的焊接电流范围内实现。使用混合电弧很容易获得光滑的正面和背面焊接表面。研究表明，将所开发的混合电弧系统应用于锁孔焊接领域，等离子弧应达到完全熔透阈值，自由弧电流用作过程调节器，可用焊接电流范围非常宽。

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引用次数: 0

Research on wafer-level SiC microgroove array process via integrated molding-etching process 通过集成成型-蚀刻工艺研究晶圆级碳化硅微槽阵列工艺

IF 6.7 2区材料科学 Q1 ENGINEERING, INDUSTRIAL

Journal of Materials Processing Technology

Pub Date : 2024-10-24 DOI: 10.1016/j.jmatprotec.2024.118645

Xiaoqiang Yao , Tianfeng Zhou , Xinbo Su , Gang Wang , Weijia Guo , Xuanzhe Yang , Bin Zhao , Xibin Wang

Silicon carbide (SiC) microgroove arrays (MGAs) play a pivotal role as optical components in modern optical engineering. This paper introduces an innovative approach for the fabrication of MGAs on hard materials. This method integrates hot embossing (HE) and inductively coupled plasma (ICP), utilizing polydimethylsiloxane (PDMS) as the intermediary mold due to its excellent demolding performance and shape replication qualities. The process involves transferring the MGAs from the Ni-P master mold to the PDMS mold, followed by replication onto the photoresist surface by hot embossing. Subsequently, the MGAs on the photoresist mask is etched into the hard substrate material using ICP etching. For efficient customization of MGAs, a reliable geometrical model based on angular dependence theory is developed to assist in selecting process parameters and designing masks. The correlation between etching selectivity and characteristic dimension is elucidated. Experimental results demonstrate that the sidewall angle decreases with higher selectivity and increases with a greater sidewall angle on the patterned mask. Plasma etching reveals unaffected areas in convex corners and the forming errors in concave corners, highlighting a high angular dependence of the etch rate. Moreover, minimizing microdefects can be achieved by optimizing process parameters and reducing etch time.

碳化硅（SiC）微槽阵列（MGA）作为光学元件在现代光学工程中发挥着举足轻重的作用。本文介绍了一种在硬质材料上制造 MGA 的创新方法。该方法整合了热压印（HE）和电感耦合等离子体（ICP），利用聚二甲基硅氧烷（PDMS）的优异脱模性能和形状复制质量作为中间模具。该工艺包括将 MGA 从 Ni-P 母模转移到 PDMS 模具，然后通过热压纹复制到光刻胶表面。随后，使用 ICP 蚀刻技术将光刻胶掩模上的 MGA 蚀刻到硬质基底材料上。为了有效定制 MGA，我们开发了一个基于角度依赖理论的可靠几何模型，以帮助选择工艺参数和设计掩膜。阐明了蚀刻选择性与特征尺寸之间的相关性。实验结果表明，选择性越高，侧壁角越小，图案化掩膜的侧壁角越大，侧壁角越大。等离子刻蚀显示了凸角不受影响的区域和凹角的成型误差，突出了刻蚀速率的高度角度依赖性。此外，通过优化工艺参数和缩短蚀刻时间，可以最大限度地减少微缺陷。

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引用次数: 0

Thermal effects and deformation mechanisms in abrasive waterjet machining: insights from Ti-6Al-4V alloy for broader applications 加砂水刀加工中的热效应和变形机制：Ti-6Al-4V 合金在更广泛应用中的启示

IF 6.7 2区材料科学 Q1 ENGINEERING, INDUSTRIAL

Journal of Materials Processing Technology

Pub Date : 2024-10-22 DOI: 10.1016/j.jmatprotec.2024.118643

Shuaikang Chang , Wenchuan Liu , Jiren Tang , Yukun Lan , Haiyang Long

As a novel cold machining method, abrasive waterjet machining (AWJM) has significant potential for processing titanium-based materials such as Ti-6Al-4V alloy. However, the thermal effects and material deformation mechanisms of AWJM remain challenging to explain. This study introduces a six-colour blackbody radiation pyrometry method that successfully monitors transient high temperatures during AWJM. The results revealed that temperatures during AWJM were not negligible, reaching up to 3602.08 K, leading to material solidification and oxidation. The flash temperature exhibited transient and continuously oscillating characteristics at the microsecond scale. The combined mechanical and thermal loads created three distinct regions: the jet impact zone (elongated grains, oxide-based compositions, and material melting), the heat-affected zone (larger grains), and the base material zone. In the jet impact zone, a pronounced temperature gradient formed on the surface, promoting grain refinement. However, as the distance from the impact zone increases, the extent of grain refinement diminishes, leading to larger grain sizes. The higher kernel average misorientation values observed in and near the impact zone indicated that high-temperature conditions were insufficient for complete recrystallisation, either because of inadequate diffusion or the short duration of the elevated temperatures. This study reveals the thermal and material deformation mechanisms involved in the AWJM process. This establishes a foundational understanding of the processing of titanium-based and other heat-sensitive materials, ultimately contributing to enhanced overall material performance.

作为一种新型冷加工方法，加砂水刀加工（AWJM）在加工钛基材料（如 Ti-6Al-4V 合金）方面具有巨大潜力。然而，AWJM 的热效应和材料变形机制仍难以解释。本研究介绍了一种六色黑体辐射测温方法，该方法可成功监测 AWJM 过程中的瞬态高温。结果表明，AWJM 过程中的温度不容忽视，最高可达 3602.08 K，导致材料凝固和氧化。闪蒸温度表现出微秒级的瞬态和连续振荡特性。机械和热负荷共同作用产生了三个不同的区域：射流冲击区（细长晶粒、氧化物成分和材料熔化）、热影响区（较大晶粒）和基体材料区。在射流冲击区，表面形成了明显的温度梯度，促进了晶粒细化。然而，随着与撞击区距离的增加，晶粒细化程度减弱，导致晶粒尺寸变大。在冲击区内和冲击区附近观察到的较高的晶核平均错向值表明，由于扩散不足或高温持续时间较短，高温条件不足以使晶粒完全再结晶。这项研究揭示了 AWJM 过程中涉及的热和材料变形机制。这为钛基材料和其他热敏材料的加工奠定了基础，最终有助于提高材料的整体性能。

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引用次数: 0

Understanding the grain refinement and residual stress formation mechanisms of a Ni-based alloy during machining processes 了解镍基合金在加工过程中的晶粒细化和残余应力形成机制

IF 6.7 2区材料科学 Q1 ENGINEERING, INDUSTRIAL

Journal of Materials Processing Technology

Pub Date : 2024-10-21 DOI: 10.1016/j.jmatprotec.2024.118641

Tao Wu , Litao Chang , Wenjun Liang , Xiaoli Li , Li Guo , Xingtai Zhou

Ni-based alloys are important materials for many industries, microstructure of the sub-surface regions of these alloys can be refined during machining processes, affecting both their machinability and service performance. Several mechanisms have been proposed to explain the machining-induced microstructure refinement of these alloys, however, sound evidences to support them are still lacking. In this research, microstructure characterization with an emphasis on the micro-texture and defects was conducted on milled surfaces of a Ni-based alloy, to promote in-depth understanding of the grain-refinement process. A nano-crystalline layer consisted a topmost region with randomly-orientated grains and annealing nano-twins and a textured region beneath it with deformed microstructure was observed in the cross-section of the alloy with the help of high resolution orientation determination techniques. These observations provide additional evidences to support the recrystallization induced grain-refinement mechanism of the nano-grains. It is also suggested that recrystallization was a by-product of the shear deformation occurred during the milling process, supported by the observation of the clear boundary between the nano-grain layer and its beneath deformed region. The deformed region was refined as a result of mechanical twining and twin-intersections, leading to significant fluctuations of the residuals stresses.

镍基合金是许多行业的重要材料，在加工过程中，这些合金表面下区域的微观结构会被细化，从而影响其加工性能和使用性能。人们提出了几种机制来解释这些合金在加工过程中引起的微观结构细化，但仍然缺乏可靠的证据来支持这些机制。本研究对一种镍基合金的铣削表面进行了微结构表征，重点是微观纹理和缺陷，以促进对晶粒细化过程的深入了解。在高分辨率取向测定技术的帮助下，在合金的横截面上观察到了由顶部区域的随机取向晶粒和退火纳米孪晶组成的纳米结晶层，以及其下方具有变形微观结构的纹理区域。这些观察结果为支持纳米晶粒的再结晶诱导晶粒细化机制提供了更多证据。此外，通过观察纳米晶粒层与其下方变形区域之间的清晰边界，还发现再结晶是铣削过程中发生剪切变形的副产品。变形区的细化是机械缠绕和孪生截面的结果，导致残余应力的显著波动。

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引用次数: 0

Investigating the effects of powder feeding rate on microstructure transformation in linear laser beam additive manufactured thick-walled structures 研究粉末进料速度对线性激光束添加剂制造厚壁结构微观结构转变的影响

IF 6.7 2区材料科学 Q1 ENGINEERING, INDUSTRIAL

Journal of Materials Processing Technology

Pub Date : 2024-10-21 DOI: 10.1016/j.jmatprotec.2024.118642

Tao Yang , Yi Luo , Chencheng Zheng , Chenlin Yang , Hui Huang

The coarse columnar crystals that grow through multiple layers are commonly observed in laser additive manufactured structures, with fractures tending to occur in regions where there are abrupt changes in grain morphology. This can lead to a degradation of the mechanical properties of the samples. In this study on laser additive manufacturing, thick-walled structures made of 304 stainless steel were created using a linear beam spot with a rectangular powder feeding nozzle. By adjusting the powder feeding rate to influence the thermal cycling characteristics during the laser additive manufacturing process, a hierarchical grain structure that combines coarse and fine equiaxed grains was achieved, enhancing the forming efficiency and overall mechanical performance of the structure. The results from the thermal cycling characteristics and microstructure analysis indicate that increasing the powder feeding rate during the additive manufacturing process can decrease the hierarchical cooling rate, temperature gradient, and heat accumulation effect. This reduction in turn decreases the grain size and facilitates the transformation of columnar crystals into equiaxed crystals. Furthermore, the transformation of low-angle grain boundaries into high-angle grain boundaries in the interlayer region helps to reduce stress concentration, weaken anisotropic tendencies, and mitigate intergranular fracture tendencies, ultimately improving the mechanical properties of the overall structure. In actual engineering applications, the powder flow can be adjusted to control the temperature gradient and cooling rate of the deposition layer, thereby altering the grain morphology and optimizing the mechanical properties of additive manufacturing parts.

在激光添加剂制造的结构中经常可以观察到通过多层生长的粗柱状晶体，而断裂往往发生在晶粒形态发生突然变化的区域。这会导致样品的机械性能下降。在这项关于激光快速成型的研究中，使用带有矩形送粉喷嘴的线性光束光斑制造了由 304 不锈钢制成的厚壁结构。在激光增材制造过程中，通过调整送粉速度来影响热循环特性，实现了粗细等轴晶粒相结合的分层晶粒结构，提高了结构的成型效率和整体机械性能。热循环特性和微观结构分析的结果表明，在增材制造过程中提高粉末喂料速率可降低分层冷却速率、温度梯度和热累积效应。这种降低反过来又会减小晶粒尺寸，促进柱状晶向等轴晶的转变。此外，层间区域的低角度晶界转变为高角度晶界有助于减少应力集中，削弱各向异性倾向，减轻晶间断裂倾向，最终改善整体结构的机械性能。在实际工程应用中，可以通过调整粉末流动来控制沉积层的温度梯度和冷却速度，从而改变晶粒形态，优化增材制造部件的机械性能。

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引用次数: 0

On influence of microstructural anisotropy of additive manufactured structures upon machining dynamics: An example of milling of Ti6Al4V thin-walled parts 增材制造结构的微结构各向异性对加工动力学的影响：以铣削 Ti6Al4V 薄壁零件为例

IF 6.7 2区材料科学 Q1 ENGINEERING, INDUSTRIAL

Journal of Materials Processing Technology

Pub Date : 2024-10-20 DOI: 10.1016/j.jmatprotec.2024.118644

Dongbo Hong , Shusong Zan , Kieran Winter , Zhirong Liao , Dragos Axinte

Thin-walled structures, as common component specification for aerospace components, easily experience deformation and chatter issues during machining (e.g. milling) operations. With Additively Manufactured (AM) materials being increasingly applied in these areas, it is found that their microstructural anisotropy can lead to varied mechanical properties and machinability in different directions. However, former research on thin-walled parts mainly focused on bulk materials, while the machining performance of these thin-wall structures produced from AM processes remains unclear. In this view, this research aims to reveal the effect of microstructural anisotropy resulting from AM process on the machining (deformation and stability) of thin-walled parts by taking Ti6Al4V as an example. Three kinds of AM Ti6Al4V thin-walled parts were fabricated with different laser scanning strategies, in which the prior columnar β grains were found to grow along the building direction and led to a variation in mechanical properties. Owing to this, the deformation and machining stability varied in the AM thin-walled parts with different β phase crystallization orientations on the same milling directions, which could be attributed to the changes of cutting force and dynamic parameters (e.g., frequency, stiffness (determined by elastic modulus), damping ratio) in different orientations. This investigation could provide a reference for the selection of printing strategies and follow-up machining process of AM thin-walled parts when considering their microstructural anisotropy.

薄壁结构作为航空航天部件的常见组件规格，在加工（如铣削）过程中很容易出现变形和颤振问题。随着快速成型（AM）材料越来越多地应用于这些领域，人们发现其微观结构的各向异性可导致不同方向的机械性能和可加工性。然而，以往对薄壁零件的研究主要集中在块体材料上，而对 AM 工艺生产的这些薄壁结构的加工性能仍不清楚。有鉴于此，本研究旨在以 Ti6Al4V 为例，揭示 AM 工艺产生的微观结构各向异性对薄壁零件加工（变形和稳定性）的影响。采用不同的激光扫描策略制造了三种 AM Ti6Al4V 薄壁零件，发现先期柱状 β 晶粒沿构建方向生长，并导致了机械性能的变化。因此，在同一铣削方向上，不同β相结晶取向的 AM 薄壁零件的变形和加工稳定性也不同，这可能是由于不同取向的切削力和动态参数（如频率、刚度（由弹性模量确定）、阻尼比）发生了变化。考虑到 AM 薄壁零件的微观结构各向异性，这项研究可为选择打印策略和后续加工工艺提供参考。

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引用次数: 0

Graphene reinforced magnesium metal matrix composites by infiltrating coated-graphene preform with melt 通过将涂覆石墨烯预型件渗入熔体实现石墨烯增强镁金属基复合材料

IF 6.7 2区材料科学 Q1 ENGINEERING, INDUSTRIAL

Journal of Materials Processing Technology

Pub Date : 2024-10-19 DOI: 10.1016/j.jmatprotec.2024.118639

Kang Yun , Jiming Zhou , Chentong Zhao , Xuemeng Jiang , Lehua Qi

Graphene’s exceptional mechanical, electrical, and thermal conductivity capabilities make it an ideal reinforcement for metal matrix composites. However, graphene is hard to be dispersed in the melt metal due to its high surface energy, non-wetting nature, and strong van der Waals interactions between graphene sheets, which weaken the reinforcing eﬃciency of composites. A novel process by infiltrating the coated-graphene preform with melt magnesium was proposed to improve the dispersion of graphene in the magnesium matrix. Graphene preforms with oriented pores were prepared by a directional freeze-drying method. Magnesium oxide coatings were deposited on the surface of graphene inside the graphene preform using the evaporation of magnesium atoms to enhance the strength as well as the wettability between the preform and magnesium matrix. Magnesium matrix composites were fabricated by liquid-solid pressure inﬁltrating coated-graphene preform with molten magnesium. The microstructure of graphene preforms and composites and mechanical properties of the composites were characterized. The results show that graphene is uniformly dispersed in the matrix and presents a reticular structure, and the hardness, elastic modulus, and compressive strength of the composite were improved apparently compared to the matrix. This study suggests that the method of preparing composites by inﬁltration provides a novel strategy for fabricating nano-material reinforced magnesium matrix composites.

石墨烯具有优异的机械、导电和导热性能，是金属基复合材料的理想增强材料。然而，由于石墨烯的高表面能、非润湿性以及石墨烯片之间强烈的范德华相互作用，石墨烯很难分散在熔融金属中，从而削弱了复合材料的增强能力。为了提高石墨烯在镁基体中的分散性，研究人员提出了一种新工艺，即在涂覆石墨烯预型件中渗入镁熔体。通过定向冷冻干燥法制备了具有定向孔隙的石墨烯预型件。利用镁原子蒸发在石墨烯预型件内部的石墨烯表面沉积氧化镁涂层，以增强预型件和镁基体之间的强度和润湿性。镁基复合材料是通过将涂覆石墨烯预型件与熔融镁进行液-固压力渗透而制成的。对石墨烯预型件和复合材料的微观结构以及复合材料的机械性能进行了表征。结果表明，石墨烯均匀地分散在基体中并呈现网状结构，与基体相比，复合材料的硬度、弹性模量和抗压强度明显提高。这项研究表明，用渗透法制备复合材料的方法为制造纳米材料增强的镁基复合材料提供了一种新策略。

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引用次数: 0

Subsurface damage and brittle fracture suppression of monocrystalline germanium in ultra-precision machining by multiple ion implantation surface modification 多重离子注入表面改性在超精密加工中抑制单晶锗的表层下损伤和脆性断裂

IF 6.7 2区材料科学 Q1 ENGINEERING, INDUSTRIAL

Journal of Materials Processing Technology

Pub Date : 2024-10-18 DOI: 10.1016/j.jmatprotec.2024.118640

Yi Tan , Wai Sze Yip , Te Zhao , Suet To , Zejia Zhao

Monocrystalline germanium has been widely used in semiconductor industry and optical engineering because of its excellent electrical and optical properties. However, its hard and brittle properties present difficulties in ultra-precision machining, resulting in surface cracks due to brittle mode cutting. A lot of research has been done on ultra-precision machining of single crystal materials to improve their machinability, including ion implantation surface modification. The ultra-precision manufacturing of semiconductor single crystal materials still faces great challenges. The optimization of ion implantation strategy and the cutting mechanism of samples after ion implantation are still problems that need to be solved. This study presents a novel surface modification strategy for germanium using multi-ion implantation to improve its machinability. In this study, simulation software visualizes the distribution and induced displacement of implanted ions on the subsurface of a germanium wafer. Ultra-precision diamond scratching experiments confirm the improved cutting performance of the ion-implanted germanium, demonstrating a significant increase in the ductile cutting region. The deformation mechanism of different modified layers of germanium during cutting was studied by TEM. The results showed that the subsurface damage of germanium after ion implantation was effectively suppressed. Finally, the microcrack free microlens array was successfully fabricated on the surface of ion-implanted germanium, demonstrating the improved machinability of germanium through ion implantation. This study broke through the limitation of surface modification by single ion implantation, deepened the understanding of brittle-ductile transition in ultra-precision machining of monocrystalline germanium, and provided theoretical basis and technical support for optimizing ion implantation assisted machining of single crystal materials in the future.

单晶锗因其优异的电气和光学特性而被广泛应用于半导体工业和光学工程领域。然而，它的硬脆特性给超精密加工带来了困难，脆性模式切削会导致表面裂纹。为了提高单晶材料的可加工性，人们对其超精密加工进行了大量研究，包括离子注入表面改性。半导体单晶材料的超精密加工仍面临巨大挑战。离子注入策略的优化和离子注入后样品的切割机制仍是亟待解决的问题。本研究提出了一种新型的多离子注入锗表面改性策略，以提高其可加工性。在这项研究中，模拟软件将植入离子在锗晶片亚表面的分布和诱导位移可视化。超精密金刚石划痕实验证实，离子注入锗的切割性能得到改善，韧性切割区域显著增加。通过 TEM 研究了切割过程中不同改性锗层的变形机制。结果表明，离子注入后锗的表层下损伤得到了有效抑制。最后，在离子注入锗表面成功制造出了无微裂纹的微透镜阵列，证明离子注入技术提高了锗的可加工性。该研究突破了单离子注入表面改性的局限性，加深了对单晶锗超精密加工中脆-韧性转变的理解，为今后优化离子注入辅助加工单晶材料提供了理论依据和技术支持。

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引用次数: 0

Coupling CPFE-CA simulation for grain refinement in ultrasonic elliptical vibration diamond cutting of polycrystalline Cu 耦合 CPFE-CA 仿真用于多晶铜超声波椭圆振动金刚石切割中的晶粒细化

IF 6.7 2区材料科学 Q1 ENGINEERING, INDUSTRIAL

Journal of Materials Processing Technology

Pub Date : 2024-10-18 DOI: 10.1016/j.jmatprotec.2024.118638

Wenxin Zhang , Zhanfeng Wang , Junjie Zhang

While microstructure evolution is commonly observed in severe plastic deformation of polycrystalline metals, modulating the cutting-induced grain refinement in subsurface of polycrystalline metals is promising for promoting the performance of machined surface. In this study, we demonstrate the effectiveness of applying ultrasonic vibration assistance (UVA) in effectively grain refinement of polycrystalline Cu in ultra-precision diamond cutting by experiments and multiscale coupling simulations. Specifically, ordinary cutting (OC) and ultrasonic elliptical vibration-assisted cutting (UEVC) experiments of polycrystalline Cu are carried out, and subsequent cross-sectional characterizations of microstructure evolution in subsurface by metallurgical microscope and electron backscatter diffraction, as well as instrumented nanoindentation tests, are performed, which jointly demonstrate significantly promoted grain refinement in subsurface and increased machined surface hardness by UVA, due to increased dislocation density that is beneficial for the nucleation and growth of dynamic recrystallization. In particular, the multi-scale coupling of Crystal Plasticity Finite Element (CPFE) simulation and Cellular Automata (CA) method is firstly established for exploring the microstructural evolution during UEVC and OC of polycrystalline Cu, which is capable of elucidating the underlying correlation of grain refinement behavior in subsurface with characteristics of stress and strain fields in cutting area. Furthermore, the influence of amplitude on the propensity of grain refinement is experimentally and theoretically evaluated, which suggests a critical amplitude of 4 μm that leads to a maximum reduction in grain size by 80.9 % and a maximum increase in machined surface hardness by 55.8 % in UEVC from that in OC, because of the mostly pronounced strain accumulation and dislocation activity. The findings reported in this study demonstrate the effectiveness of applying ultrasonic vibration assistance for modulating the grain refinement accompanying strengthening of machined surface in ultra-precision diamond cutting of polycrystalline metals.

多晶金属在剧烈塑性变形过程中通常会出现微观结构演变，而调节多晶金属表层下的切削诱导晶粒细化有望提高加工表面的性能。在本研究中，我们通过实验和多尺度耦合模拟证明了在超精密金刚石切削中应用超声波振动辅助（UVA）有效细化多晶铜晶粒的有效性。具体而言，对多晶铜进行了普通切削（OC）和超声椭圆振动辅助切削（UEVC）实验，随后通过金相显微镜和电子反向散射衍射以及仪器纳米压痕测试对次表层的微观结构演变进行了横截面表征，共同证明了 UVA 显著促进了次表层的晶粒细化并提高了加工表面硬度，这是由于位错密度的增加有利于动态再结晶的成核和生长。其中，首次建立了晶体塑性有限元（CPFE）模拟和细胞自动机（CA）方法的多尺度耦合，用于探索多晶铜在 UEVC 和 OC 过程中的微观结构演变，能够阐明次表层晶粒细化行为与切削区域应力场和应变场特征的内在关联。此外，还通过实验和理论评估了振幅对晶粒细化倾向的影响，结果表明 4 μm 的临界振幅可使 UEVC 中的晶粒尺寸最大减小 80.9%，加工表面硬度最大提高 55.8%，而 OC 中的晶粒尺寸减小和提高主要是由于明显的应变积累和位错活动。本研究报告的结果表明，在多晶金属的超精密金刚石切削中，应用超声波振动辅助调节晶粒细化和强化加工表面非常有效。

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