Journal of Materials Processing Technology最新文献_第5页

Plasma-assisted polishing with silicon and silica plates: Comparison of interaction mechanism and achievement of atomically flat surfaces on single- and polycrystalline diamond 等离子体辅助抛光硅和硅片：单晶和多晶金刚石原子平面的相互作用机制和实现的比较

IF 7.5 2区材料科学 Q1 ENGINEERING, INDUSTRIAL

Journal of Materials Processing Technology

Pub Date : 2025-12-16 DOI: 10.1016/j.jmatprotec.2025.119187

Jiayuan Dong , Sota Sugihara , Kafumi Fujiwara , Rongyan Sun , Yuji Ohkubo , Junsha Wang , Tadatomo Suga , Kazuya Yamamura

Due to its extreme hardness and chemical stability, diamond poses significant challenges for traditional machining processes. Plasma-assisted polishing (PAP) is a recently developed technique that integrates chemically active species from plasma with mechanical polishing, offering great potential for highly efficient and precise surface finishing of diamond materials. In this study, the polishing characteristics of silicon and silica plates were comprehensively investigated. The results confirmed the superiority of the silicon plate, which produced a smoother diamond surface and achieved a higher material removal rate (MRR) during PAP. To clarify the origin of this difference, the synergistic role of plasma irradiation was examined, as plasma is known to significantly enhance both the MRR and surface quality of diamond. Accordingly, X-ray photoelectron spectroscopy (XPS) measurements combined with density functional theory (DFT) calculations were conducted to gain deeper insights into the underlying mechanisms. The analyses revealed that both the polishing plate material and plasma irradiation play crucial roles in the PAP process. The higher chemical reactivity of silicon promotes bond formation at the tribological interface, thereby facilitating carbon removal. Meanwhile, oxygen radicals generated by plasma participate in interfacial reactions by oxidizing both the diamond and the polishing plate surface, as well as promoting the formation of oxygen-bridge bonds. This process enhances the diamond removal rate but simultaneously accelerates wear of the polishing plate surface. To further evaluate this effect, a long-duration polishing experiment was performed to investigate plate wear. The results showed that as wear progresses, the plate surface becomes smoother, leading to a decline in both polishing accuracy and the MRR of the diamond substrate. To counteract this effect, laser dressing was introduced to restore and sustain surface roughness, and its effectiveness was experimentally confirmed. Finally, PAP was applied to a 2-inch polycrystalline diamond substrate, achieving a grain-boundary step-free surface with a surface roughness (Sa) of approximately 0.3 nm. These findings provide practical guidance for the ultra-precision machining of diamond, deepen the understanding of coupled chemical–mechanical interactions at the tribological interface, and support the advancement of diamond-based components in semiconductor applications.

由于其极高的硬度和化学稳定性，金刚石对传统的加工工艺提出了重大挑战。等离子体辅助抛光（PAP）是最近发展起来的一项技术，它将等离子体中的化学活性物质与机械抛光相结合，为金刚石材料的高效、精确表面抛光提供了巨大的潜力。本文对硅及硅片的抛光特性进行了全面的研究。结果证实了硅板的优越性，它产生了更光滑的金刚石表面，并且在PAP过程中实现了更高的材料去除率（MRR）。为了澄清这种差异的来源，我们研究了等离子体辐照的协同作用，因为等离子体可以显著提高金刚石的MRR和表面质量。因此，x射线光电子能谱（XPS）测量与密度泛函理论（DFT）计算相结合，以深入了解潜在的机制。分析表明，抛光板材料和等离子体辐照在PAP过程中起着至关重要的作用。硅较高的化学反应活性促进了摩擦学界面的键形成，从而促进了碳的去除。同时，等离子体产生的氧自由基通过氧化金刚石和抛光片表面参与界面反应，促进氧桥键的形成。该工艺提高了金刚石的去除率，但同时也加速了抛光板表面的磨损。为了进一步评估这种效果，进行了长时间抛光实验，研究了板的磨损情况。结果表明：随着磨损的加剧，金刚石基体表面变得更加光滑，抛光精度和MRR均有所下降；为了抵消这种影响，引入激光修整来恢复和维持表面粗糙度，并通过实验证实了其有效性。最后，将PAP应用于2英寸的多晶金刚石衬底上，获得了表面粗糙度（Sa）约为0.3 nm的晶界无台阶表面。这些发现为金刚石的超精密加工提供了实践指导，加深了对摩擦学界面上耦合化学-机械相互作用的理解，并支持了金刚石基元件在半导体应用中的进步。

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引用次数: 0

Modeling composition-dependent melt dynamics and defect formation in multi-material additive manufacturing 多材料增材制造中依赖成分的熔体动力学和缺陷形成建模

IF 7.5 2区材料科学 Q1 ENGINEERING, INDUSTRIAL

Journal of Materials Processing Technology

Pub Date : 2025-12-15 DOI: 10.1016/j.jmatprotec.2025.119185

Arvind Chouhan , Lutz Mädler , Nils Ellendt

Multi-material laser powder bed fusion (PBF-LB/M) enables the fabrication of components with tailored properties for advanced applications. However, large differences in thermophysical behavior between alloys such as Cu and SS316L introduce processing challenges, including lack of fusion, porosity, and thermal cracking at material interfaces. In this study, a coupled Discrete Element Method-Computational Fluid Dynamics (DEM-CFD) framework with a Volume of Fluid (VOF) methodology is developed to investigate melt pool dynamics, interfacial mixing, and solidification in laser powder bed fusion of Cu-SS316L. The model accounts for temperature and composition dependent thermophysical properties, diffusion-driven species transport, and laser–material interaction through a ray-tracing approach. Experimental validation is conducted to support the numerical findings. Simulations reveal that high Cu content results in smaller melt pools and lack of fusion defects due to Cu's high reflectivity and thermal diffusivity, whereas SS316L rich regions produce larger melt pools, reducing fusion defects but increasing keyhole porosity risk. At the Cu-SS316L interface, asymmetric melting and rapid solidification on the Cu side limit mixing, forming sharp diffusion boundaries. Steep thermal gradients across the interface induce differential thermal expansion, leading to thermal crack formation, particularly under high energy input. To mitigate such defects, a material grading strategy is proposed to smooth thermal gradients and reduce residual stresses. The proposed numerical framework offers critical insights into the mixing mechanisms at dissimilar interfaces for optimizing the multi-material PBF-LB/M process.

多材料激光粉末床融合（PBF-LB/M）能够制造具有定制性能的组件，用于高级应用。然而，Cu和SS316L等合金在热物理行为上的巨大差异给加工带来了挑战，包括缺乏熔合、气孔和材料界面的热裂。本研究采用离散元法-计算流体动力学（DEM-CFD）框架和流体体积（VOF）方法，研究了Cu-SS316L激光粉末床熔炼过程中熔池动力学、界面混合和凝固过程。该模型考虑了温度和成分相关的热物理性质、扩散驱动的物质输运以及通过射线追踪方法进行的激光-材料相互作用。实验验证了数值结果。模拟结果表明，由于Cu的高反射率和热扩散系数，高Cu含量导致熔池较小，熔合缺陷较少，而富含SS316L的区域熔池较大，熔合缺陷减少，但增加了锁孔孔隙风险。在Cu- ss316l界面处，Cu侧的不对称熔化和快速凝固限制了混合，形成了尖锐的扩散边界。界面上陡峭的热梯度诱导了不同的热膨胀，导致热裂纹的形成，特别是在高能量输入下。为了减轻这些缺陷，提出了一种材料分级策略，以平滑热梯度和减少残余应力。所提出的数值框架为优化多材料PBF-LB/M工艺提供了不同界面下混合机制的关键见解。

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引用次数: 0

A powder-bed in-situ modification strategy for surface quality enhancement in laser powder bed fusion: A case study on oxide ceramics 提高激光粉末床熔合表面质量的粉末床原位改性策略——以氧化陶瓷为例

IF 7.5 2区材料科学 Q1 ENGINEERING, INDUSTRIAL

Journal of Materials Processing Technology

Pub Date : 2025-12-13 DOI: 10.1016/j.jmatprotec.2025.119184

Yuji Li , Jin Huang , Zhenghua Liu , Delong Shi , Beining Li , Weiwei He , Fanbo Meng

In the Laser Powder Bed Fusion (LPBF) forming process of oxide ceramics, Due to the inherently loose structure of the powder bed and the poor thermal conductivity of oxide ceramics, issues such as intense melt pool spattering and uneven melting/solidification frequently arise. To address this challenge, this study proposes an in-situ modulation and modification strategy for the powder bed. Thermal and kinetic models were established to analyze the melting process of the modified powder bed, and multi-scale validation was conducted in conjunction with experimental work.The modified powder bed demonstrates significant suppression of melt pool spattering behavior.Compared with the unmodified control samples, the modified components exhibited reductions in surface roughness values Ra and Rz by 88.6 % and 28.6 %, respectively. In-depth mechanistic analysis revealed that the auxiliary materials infiltrated the interparticle gaps by capillary forces, and sol gelation substantially enhanced the interparticle bonding strength. This phenomenon effectively restrained the particle spattering dynamics under recoil pressure. Concurrently, the incomplete combustion of benzyl alcohol generated an in situ nanoscale carbon layer on the powder bed surface, reducing the melt-pool temperature gradients. This phenomenon weakens the Marangoni convection intensity driven by the surface tension gradients, thereby extending the time window for melt spreading and leveling. The in-situ powder bed modulation and modification strategy provides a new theoretical basis for improving the forming quality and microstructural optimization of oxide ceramic components fabricated by LPBF. Importantly, this strategy offers a novel process pathway for addressing melt pool instability and defect control in LPBF of various material systems.

在氧化物陶瓷的激光粉末床熔合成形过程中，由于粉末床本身的松散结构和氧化物陶瓷的导热性差，经常出现熔池飞溅剧烈和熔化/凝固不均匀等问题。为了解决这一挑战，本研究提出了一种粉末床的原位调制和改造策略。建立了热学和动力学模型，分析了改性粉末床的熔化过程，并结合实验工作进行了多尺度验证。改性粉末床对熔池溅射行为有明显的抑制作用。与未改性的对照样品相比，改性组分的表面粗糙度值Ra和Rz分别降低了88.6% %和28.6% %。深入的机理分析表明，辅助材料通过毛细力渗透颗粒间隙，溶胶凝胶作用大大增强了颗粒间的结合强度。这种现象有效地抑制了粒子在反冲压力下的溅射动力学。同时，苯甲醇的不完全燃烧在粉末床表面形成纳米级碳层，减小了熔池温度梯度。这一现象减弱了由表面张力梯度驱动的Marangoni对流强度，从而延长了熔体扩散和流平的时间窗。粉末床原位调制和改性策略为提高LPBF制备的氧化陶瓷元件的成形质量和优化微结构提供了新的理论依据。重要的是，该策略为解决各种材料体系的LPBF熔池不稳定性和缺陷控制提供了一种新的工艺途径。

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引用次数: 0

Uniform aluminum droplet deposition manufacturing in an open environment: Oxidation suppression and stable printing under coaxial shielding gas 开放环境下均匀铝滴沉积制造：同轴保护气体下的抗氧化和稳定印刷

IF 7.5 2区材料科学 Q1 ENGINEERING, INDUSTRIAL

Journal of Materials Processing Technology

Pub Date : 2025-12-11 DOI: 10.1016/j.jmatprotec.2025.119183

Yi Zhou , Jun Luo , Lin Su , Lehua Qi

Employing opening shielding gas in metal micro-droplet deposition enables lightweight, real-time, eco-friendly manufacturing. However, aluminum alloys, highly sought-after for manufacturing, face challenges in equipment development and experimental research due to their high oxidation reactivity and thermal sensitivity. This study presents a novel approach that combines piezoelectric actuation with dynamic coaxial gas shielding. The method enables stable aluminum droplet printing with micron-level precision in an open environment. Through combined experiments and theoretical models, the impact of oxidation on droplet deposition dynamics, surface morphology, and formation quality was investigated. Results show that even a slight change in the deposition distance would cause significant variations in deposition and oxidation behavior. Increasing the deposition distance not only exacerbates droplet oxidation and dampens droplet oscillation, but also forms oxidation wrinkles on the droplet surface. A higher substrate feed speed also reduces the shielding gas effectiveness. This effect is particularly significant in multi-layer droplet pileup, where heat accumulation delays solidification and exacerbates oxidation in the upper-layer droplets. To address these challenges, a variable-speed printing strategy based on thermal management was proposed. This method suppresses droplet surface oxidation, enabling metallurgical bonding and stable part formation in open environments. This work provides both practical strategies and theoretical insights for oxidation control in high-temperature metal droplet printing under open-environment conditions.

在金属微滴沉积中采用开口保护气体，实现了轻量化、实时、环保的制造。然而，铝合金由于具有较高的氧化反应性和热敏性，在制造业中备受追捧，在设备开发和实验研究方面面临挑战。本文提出了一种将压电驱动与动态同轴气体保护相结合的新方法。该方法可在开放环境下实现微米级精度的稳定铝滴打印。通过实验和理论模型相结合的方法，研究了氧化对液滴沉积动力学、表面形貌和地层质量的影响。结果表明，即使沉积距离的微小变化也会引起沉积和氧化行为的显著变化。增大沉积距离不仅会加剧液滴氧化，抑制液滴振荡，还会在液滴表面形成氧化皱纹。较高的衬底进给速度也会降低保护气体的有效性。这种效应在多层液滴堆积中尤为显著，在多层液滴堆积中，热量积累延迟了凝固并加剧了上层液滴的氧化。为了解决这些问题，提出了一种基于热管理的变速打印策略。这种方法抑制液滴表面氧化，使冶金结合和稳定的零件形成在开放的环境。这项工作为开放环境下高温金属液滴打印氧化控制提供了实践策略和理论见解。

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引用次数: 0

Enhancing strain recovery ratio of NiTi ultrasonic spot welding joints via electric current treatment induced dislocations and precipitates 通过电流处理诱发位错和析出相，提高镍钛超声点焊接头应变恢复率

IF 7.5 2区材料科学 Q1 ENGINEERING, INDUSTRIAL

Journal of Materials Processing Technology

Pub Date : 2025-12-10 DOI: 10.1016/j.jmatprotec.2025.119182

Zhiyuan Xu, Jinzhe Li, Kuangji Zhu, Yansong Zhang

This study investigates the fundamental effects of electric current treatment (ECT) on the microstructural evolution and functional performance of NiTi shape memory alloy (SMA) ultrasonic spot welding (USW) joints. Under optimal parameters (100 A, 2 min), the joints exhibit the highest recovery ratio during cyclic tensile testing. The enhancement arises from the intrinsic role of the electric current in regulating material performance: Electric current treatment accelerates elemental diffusion and promotes the formation of a high density of fine Ni₄Ti₃ precipitates at the interface, while the electron wind force lowers the energy barrier for 1/2[111] dislocation slip, generating high-density wavy dislocations. Together, these mechanisms demonstrate controlled microstructural tailoring that directly links processing conditions to dislocation dynamics, precipitate evolution, and functional stability. These findings reveal a fundamental materials-processing strategy for actively controlling microstructure and superelastic performance in NiTi SMAs, advancing understanding beyond conventional thermal or mechanical treatments.

研究了电流处理（ECT）对NiTi形状记忆合金（SMA）超声点焊（USW）接头组织演变和功能性能的影响。在最优参数（100 A, 2 min）下，节理在循环拉伸试验中恢复率最高。这种增强源于电流对材料性能的内在调节作用：电流处理加速了元素的扩散，促进了界面处高密度的Ni4Ti3细晶析出相的形成，而电子风作用力降低了1/2[111]位错滑移的能垒，产生高密度的波浪形位错。总之，这些机制证明了受控的微观结构剪裁，将加工条件与位错动力学、沉淀演化和功能稳定性直接联系起来。这些发现揭示了一种基本的材料加工策略，可以主动控制NiTi sma的微观结构和超弹性性能，超越传统的热处理或机械处理。

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引用次数: 0

Effect of bypass cold wire spatial position on process stability and elemental transfer in submerged arc welding for in situ alloying 旁通冷丝空间位置对原位合金化埋弧焊工艺稳定性和元素传递的影响

IF 7.5 2区材料科学 Q1 ENGINEERING, INDUSTRIAL

Journal of Materials Processing Technology

Pub Date : 2025-12-10 DOI: 10.1016/j.jmatprotec.2025.119179

Zekun Yang , Zhanli Yang , Dakui Fei , Yanxu Wang , Guofu Wang , Guangnan Zhao , Xin Yuan , Bing Lu , Ziran Wang , Kai Xu

Achieving flexible and cost-effective in-situ alloying within multi-wire submerged arc welding (multi-wire SAW) represents a core challenge for manufacturing high-performance pipeline steels. This study systematically investigates how the spatial position of the alloying source (a bypass cold wire) relative to the energy source (the multi-arc system) governs the physical metallurgy during the welding process. The results reveal that the cold wire feeding position has a decisive influence on both process stability and metallurgical behavior. In this confined-arc process, the highest elemental recovery was counter-intuitively obtained in the most energy-intensive region—the coupled arc zone. However, this high-recovery process window was accompanied by severe arc instability (the average coefficient of variation for the main wire current increased from 4.20 % to 7.08 %, increasing by nearly 70 %), leading to significant chemical segregation and microstructural degradation. To explain this anomalous phenomenon and resolve the aforementioned conflict, this work proposes the "Arc Cavity Confined Reaction" model. This model, for the first time, scientifically demonstrates from the dual mechanisms of physical confinement and chemical protection how the flux-formed cavity transforms conventional arc burn-off" into a controlled "evaporation-confinement- recondensation" cycle, thereby amending the applicability of classical loss theories in confined-arc processes. Based on this theoretical framework, the "molten pool stabilization zone" behind the arcs was ultimately identified as the optimal process window to decouple elemental recovery from process stability, under which condition the weld metal's low-temperature impact toughness (-10°C) reached 165.7 J. This work fundamentally advances the understanding of elemental mass transfer in confined-arc environments, providing a new theoretical framework and critical process guidelines for all advanced materials processing technologies that rely on slag protection.

在多丝埋弧焊（multi-wire埋弧焊）中实现灵活且经济的原位合金化是制造高性能管道钢的核心挑战。本研究系统地研究了合金源（旁路冷丝）相对于能量源（多弧系统）的空间位置对焊接过程中物理冶金的影响。结果表明，冷送丝位置对工艺稳定性和冶金性能都有决定性的影响。在这种封闭电弧过程中，与直觉相反，在能量最密集的区域-耦合电弧区域获得了最高的元素回收率。然而，这个高回收率的过程窗口伴随着严重的电弧不稳定性（主线电流的平均变异系数从4.20 %增加到7.08 %，增加了近70 %），导致显著的化学偏析和微观结构退化。为了解释这一异常现象并解决上述矛盾，本文提出了“弧腔限制反应”模型。该模型首次从物理约束和化学保护的双重机制科学论证了熔剂形成的空腔如何将传统的电弧燃尽转变为受控的“蒸发-约束-再凝聚”循环，从而修正了经典损耗理论在电弧约束过程中的适用性。基于该理论框架，最终确定弧后的“熔池稳定区”是将元素恢复与工艺稳定性分离的最佳工艺窗口，在此条件下，焊缝金属的低温冲击韧性（-10°C）达到165.7 J。这项工作从根本上推进了对限弧环境中元素传质的理解，为所有依赖于渣保护的先进材料加工技术提供了新的理论框架和关键工艺指导。

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引用次数: 0

Refill friction stir spot welding of high-strength aluminium alloys: Linking hook formation and calculated heat input to microstructure and mechanical properties 高强度铝合金的再填充搅拌摩擦点焊：连接钩的形成和计算的热量输入对微观结构和机械性能的影响

IF 7.5 2区材料科学 Q1 ENGINEERING, INDUSTRIAL

Journal of Materials Processing Technology

Pub Date : 2025-12-09 DOI: 10.1016/j.jmatprotec.2025.119180

Sebastian Fritsche , Jonathan Draper , Ricardo Henrique Buzolin , Ryan Maxwell , Athanasios Toumpis , Alexander Galloway , Sergio T. Amancio-Filho

Refill Friction Stir Spot Welding is a promising technique for joining lightweight aluminium alloys such as AA7075-T6. However, hook defects—microstructural discontinuities at the weld interface—can significantly compromise joint integrity. Additionally, variations in heat input during welding influence microstructure evolution and mechanical properties. This study investigates the influence of process parameters and the hook defect on the quasi-static performance of AA7075-T6 RFSSW joints. Joints with various parameter combinations were analysed using optical microscopy, electron backscatter diffraction, tensile lap shear testing, and microhardness mapping, alongside thermocouple measurements of process temperatures. A semi-quantitative heat input model was developed to provide new insights into thermal characteristics and their effects on microstructural evolution. The obtained results show a decrease in ultimate lap shear force for high upward or downward-directed hooks. A welding time of 4 s and rotational speed of 2200 rpm resulted in optimal joint performance, achieving an ultimate lap shear force of 12.2 kN and sufficient heat input to prevent refill defects. Extended welding durations led to overheating and additional defects in the stir zone, while low welding time or rotational speed significantly influenced welding temperatures, heat input, and microstructural characteristics at the shoulder plunge path periphery. The findings emphasise the critical role of dynamic recrystallisation in the resulting microstructures and their impact on mechanical performance. Fatigue strength of the optimised joints exceeds RFSSW joints reported in the literature, underscoring the effectiveness of the selected process parameters in enhancing joint durability. Furthermore, the established semi-quantitative heat input model links energy partitioning to defect formation and microhardness of the joints. This provides new insights into the RFSSW process and enables knowledge transfer to other RFSSW applications.

再填充搅拌摩擦点焊是一种很有前途的连接轻质铝合金（如AA7075-T6）的技术。然而，钩状缺陷——焊接界面的微观组织不连续——会严重损害接头的完整性。此外，焊接过程中热量输入的变化会影响微观组织的演变和力学性能。研究了工艺参数和挂钩缺陷对AA7075-T6 RFSSW接头准静态性能的影响。使用光学显微镜、电子背散射衍射、拉伸搭接剪切测试和显微硬度图以及热电偶测量工艺温度对不同参数组合的接头进行了分析。建立了半定量的热输入模型，为热特性及其对微观组织演化的影响提供了新的见解。结果表明，高向上或向下导向的吊钩的极限搭接剪力减小。焊接时间为4 s，转速为2200 rpm，接头性能最佳，最终接合力为12.2 kN，热量输入充足，可防止再填充缺陷。延长的焊接时间会导致搅拌区过热和额外的缺陷，而较低的焊接时间或转速会显著影响焊接温度、热输入和肩部插入路径周边的显微组织特征。研究结果强调了动态再结晶在产生的微观结构及其对机械性能的影响中的关键作用。优化后的接头的疲劳强度超过了文献报道的RFSSW接头，强调了所选工艺参数在提高接头耐久性方面的有效性。建立的半定量热输入模型将能量分配与缺陷形成和接头显微硬度联系起来。这为RFSSW流程提供了新的见解，并使知识能够转移到其他RFSSW应用程序中。

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引用次数: 0

Regulation of PBF-LB/M melt pool oscillation behavior via beam shaping: A study based on time-frequency characteristics of coaxial radiation signals 光束整形对PBF-LB/M熔池振荡行为的调节：基于同轴辐射信号时频特性的研究

IF 7.5 2区材料科学 Q1 ENGINEERING, INDUSTRIAL

Journal of Materials Processing Technology

Pub Date : 2025-12-09 DOI: 10.1016/j.jmatprotec.2025.119181

Tao Zhu , Xiangjun Xiang , Qiang Gong , Jiaxing Wen , Lai Wei , Tian Huang , Hongkai Jin , Changqiu Chen , Huabin He , Kaihua Sun , Xianfeng Shen , Shuke Huang

Melt pool instability remains a critical barrier to the reliability of Powder Bed Fusion by Laser Beam Melting (PBF-LB/M). While beam shaping is a promising regulatory strategy, the underlying dynamic mechanisms governing its stabilizing effect are not yet fully resolved. By integrating in-situ radiation monitoring with multiphysics simulations on HR-2 austenitic stainless steel, this work systematically elucidates the intrinsic mechanism through which a flat-top beam mitigate melt pool oscillation. The research reveals that the uniform energy distribution of the flat-top beam fundamentally suppresses the steep temperature gradients within the melt pool and the consequent Marangoni convection, thereby significantly enhancing hydrodynamic stability. This stability was validated across multiple dimensions. Within a wide processing window (power 170–450 W, speed 500–1200 mm/s), the use of a flat-top beam, compared to a Gaussian beam, reduced the peak melt pool temperature by an average of 500°C and decreased the maximum fluid velocity by approximately 50 %. Crucially, this profound stabilization of the internal thermo-fluid dynamics is directly reflected in the time-frequency analysis of the real-time photodiode signal, which captures the thermal radiation emitted from the melt pool. The flat-top beam effectively filters out high-frequency (>1 kHz) spectral energy by over 80 %, transforming the melt pool dynamics from a stochastic, high-frequency oscillatory state driven by intense convection to a predictable, low-frequency dominant regime. Ultimately, this study establishes and verifies a cascading physical mechanism: energy homogenization leads to the mitigation of temperature gradients and peak temperatures, which in turn suppresses Marangoni flow velocity and results in a transition of melt pool oscillations from high-frequency, erratic fluctuations to low-frequency, periodic ones. This work provides a critical theoretical basis and a frequency-domain diagnostic tool for leveraging beam shaping to achieve high-stability PBF-LB/M additive manufacturing.

熔池不稳定性是影响激光熔化粉末床熔合可靠性的一个重要因素。虽然束整形是一种很有前途的调节策略，但控制其稳定效果的潜在动力机制尚未完全解决。通过将现场辐射监测与HR-2奥氏体不锈钢的多物理场模拟相结合，系统地阐明了平顶梁缓解熔池振荡的内在机制。研究表明，平顶梁的均匀能量分布从根本上抑制了熔池内陡峭的温度梯度和由此产生的Marangoni对流，从而显著提高了流体动力稳定性。这种稳定性在多个维度上得到了验证。在宽处理窗口内（功率170-450 W，速度500 - 1200 mm/s），与高斯光束相比，使用平顶光束可将熔池峰值温度平均降低500°C，并将最大流体速度降低约50% %。至关重要的是，这种内部热流体动力学的深度稳定直接反映在实时光电二极管信号的时频分析中，该信号捕获了熔池发出的热辐射。平顶光束有效地滤除高频（>1 kHz）频谱能量，滤除率超过80% %，将熔池动力学从由强烈对流驱动的随机高频振荡状态转变为可预测的低频主导状态。最终，本研究建立并验证了一个级联物理机制：能量均一化导致温度梯度和峰值温度降低，进而抑制马兰戈尼流速度，导致熔池振荡从高频、不稳定波动转变为低频、周期性波动。这项工作为利用光束整形实现高稳定性PBF-LB/M增材制造提供了关键的理论基础和频域诊断工具。

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引用次数: 0

Cold manufacturing of metallic glass-based composites by ultrasonic vibrations 金属玻璃基复合材料的超声振动冷加工

IF 7.5 2区材料科学 Q1 ENGINEERING, INDUSTRIAL

Journal of Materials Processing Technology

Pub Date : 2025-12-08 DOI: 10.1016/j.jmatprotec.2025.119178

Luyao Li , Yu Zhang , Jinbiao Huang , Zhe Chen , Xiangyang Yu , Wei Li , Jiasen Sun , Kangyu Lin , Chenchen Yuan , Jiang Ma

The design of materials with desirable and tailorable properties is a long-standing goal within materials science, where composites represent a key strategy. However, a central dilemma in conventional composite manufacturing is that the thermal energy required to form strong interfacial bonds often simultaneously induces detrimental side effects, including interfacial reactions and reinforcement degradation. To resolve this generic conflict, we introduce a versatile "cold manufacturing" strategy utilizing metallic glasses as matrices. By exploiting an athermal ultrasonic vibration mechanism—which induces transient liquid-like behavior in metallic glasses without thermal activation—we achieve seamless interfacial bonding across diverse conductors, insulators, metals, and non-metals via oxide-layer-penetrating diffusion at ambient conditions. Crucially, successful fabrication underwater and in liquid nitrogen definitively demonstrates the technique's purely athermal nature, avoiding any thermal degradation pathways. By tuning metallic glasses binder ratios and additive compositions, we precisely engineer mechanical properties (Vickers hardness: 400–1450 HV) and magnetic response (saturation magnetization: 0–158.6 emu/g), forming robust bonds. This work thus establishes a versatile and fundamentally distinct composite manufacturing platform, opening a generic pathway to multifunctional composites free from the intrinsic limitations of heat.

设计具有理想和可定制性能的材料是材料科学的长期目标，其中复合材料代表了关键策略。然而，传统复合材料制造的一个核心难题是，形成强界面键所需的热能往往同时引起有害的副作用，包括界面反应和增强物降解。为了解决这一普遍的冲突，我们引入了一种通用的“冷制造”策略，利用金属玻璃作为矩阵。通过利用非热超声振动机制（在没有热激活的情况下在金属玻璃中诱导瞬态类液体行为），我们在环境条件下通过氧化层穿透扩散实现了不同导体、绝缘体、金属和非金属之间的无缝界面结合。至关重要的是，在水下和液氮中成功制造证明了该技术的纯粹非热性质，避免了任何热降解途径。通过调整金属玻璃粘结剂比例和添加剂成分，我们精确地设计机械性能（维氏硬度：400-1450 HV）和磁响应（饱和磁化强度：0-158.6 emu/g），形成坚固的键。因此，这项工作建立了一个通用的、从根本上独特的复合材料制造平台，开辟了一条不受热量固有限制的多功能复合材料的通用途径。

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引用次数: 0

Heterogeneity-induced ductile–brittle transition behavior in negative rake angle cutting of Al/SiCp composites Al/SiCp复合材料负前角切削中非均质诱导的韧脆转变行为

IF 7.5 2区材料科学 Q1 ENGINEERING, INDUSTRIAL

Journal of Materials Processing Technology

Pub Date : 2025-12-06 DOI: 10.1016/j.jmatprotec.2025.119177

Wei Sun , Zhenlong Cheng , Yaohui Wang , Dehui Liu , Peiyao Sheng , Kui Liu , Junyun Chen , Penghui Li

The inherent heterogeneity of Al/SiCp composites caused by the limited synergetic deformation capacity between the soft Al matrix and the hard SiC particles alter the conventional ductile–brittle transition (DBT) behavior of SiC. The conventional DBT theory was originally developed for homogeneous materials. However, its applicability to Al/SiCp composites is significantly limited. Therefore, a deeper understanding of the unique DBT behavior induced by inherent heterogeneity is essential for achieving ductile-regime machining of Al/SiCp composites. This study systematically investigated the heterogeneity-induced DBT behavior of Al/SiCp composites and explored the effect of negative rake angle cutting on this behavior through plunge-cut experiments and molecular dynamics (MD) simulations. The experimental results indicate that the SiC particles at the heterogeneous interface (hetero-interface) experienced a sudden transition to a state with complete brittle-regime removal, bypassing the traditional DBT stage. However, the machined surface of SiC particles located away from the interface still underwent a normal DBT process. The MD simulations show that the abrupt brittle transition is attributed to the sustained crack propagation at the hetero-interface caused by an insufficient support for the SiC particles by the Al matrix. Both experimental and simulation results revealed that negative rake angle cutting enhanced the plastic deformation ability of the interfacial SiC particles, as evidenced by the high dislocation densities. Consequently, compared to that at a 0° tool rake angle, the brittle-regime removal at the hetero-interface was significantly postponed when the tool rake angle was negative, which was conducive to mitigating the interfacial edge collapse of SiC. Finally, a novel critical DBT distance is proposed to quantify the initiated location at the hetero-induced brittle removal of SiC particles, serving as an evaluation parameter for the magnitude of interfacial edge collapses. From this perspective, the particle-removal behavior of Al/SiCp composites cannot be solely determined using the traditional DBT depth; a comprehensive consideration of the critical DBT distance dominated by the interfacial heterogeneity is also required to achieve ductile-regime machining.

软Al基体与硬SiC颗粒之间有限的协同变形能力导致Al/SiCp复合材料固有的非均质性改变了SiC传统的韧脆转变行为。传统的DBT理论最初是针对均匀材料发展起来的。然而，其在Al/SiCp复合材料中的适用性明显受到限制。因此，更深入地了解由固有非均质性引起的独特DBT行为对于实现Al/SiCp复合材料的延性加工至关重要。本研究系统地研究了Al/SiCp复合材料的非均质诱导DBT行为，并通过冲切实验和分子动力学（MD）模拟探讨了负前角切割对该行为的影响。实验结果表明，在非均相界面处的SiC颗粒跳过传统的DBT阶段，突然过渡到脆性完全去除的状态。然而，远离界面的SiC颗粒的加工表面仍然经历了正常的DBT过程。MD模拟结果表明，突变脆性转变是由Al基体对SiC颗粒的支撑不足引起的异质界面处持续裂纹扩展引起的。实验和模拟结果均表明，负前角切削增强了界面SiC颗粒的塑性变形能力，表现为位错密度高。因此，与刀具前倾角为0°时相比，当刀具前倾角为负时，异质界面处脆性状态的去除明显推迟，有利于减轻SiC的界面边缘坍塌。最后，提出了一种新的临界DBT距离，用于量化SiC颗粒异质脆性去除的起始位置，作为界面边缘坍塌程度的评估参数。从这个角度来看，Al/SiCp复合材料的颗粒去除行为不能仅仅用传统的DBT深度来确定；为了实现延性加工，还需要综合考虑由界面非均质性主导的临界DBT距离。

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引用次数: 0