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Improving fusion zone microstructure inhomogeneity in dissimilar-metal welding by laser welding with oscillation
摘要： Laser processing of welding with oscillation was adopted to weld dissimilar metals of Ni-Cr-Mo and Cu-Cr-Zr so as to prevent the generation of the macroscopic segregation. Analyses of morphology, element distribution and mechanical property were carried out to investigate the effect of oscillation on dissimilar-metal welding. The results indicated that with the application of oscillation of laser, the poor mixing zone and the partial melting strengthening phases were obviously reduced, and the distribution of main constituent elements was more uniform. Due to the better effect of solid solution strengthening, the maximum increment of the tensile strength and elongation could approximately be up to 20% and 45%, respectively.
关键词： Segregation,Dissimilar-metal,Laser processing,Welding,Microstructure
更新于2025-09-12 10:27:22
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Metal ablation study with a 10 picosecond laser under low and median fluence
摘要： Single shot 10 ps laser ablation on aluminium and gold at a wavelength of 1064 nm under low and median laser fluence was studied theoretically and experimentally. Simulations have been performed by using an optimized two temperature model. It is revealed that electron-phonon coupling ability of the target metal affected both the ablation depth and target metal’s morphology. Under low fluence, melting could well be the relevant ablation mechanism. With laser fluence rising, vaporization or phase explosion happens thereafter, depending on material’s electron-phonon coupling ability.
关键词： Metals and alloys,Picosecond laser processing,Modeling of laser ablation
更新于2025-09-11 14:15:04
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In-Situ and Ex-Situ Characterization of Femtosecond Laser-Induced Ablation on As2S3 Chalcogenide Glasses and Advanced Grating Structures Fabrication
摘要： Femtosecond laser pulse of 800 nm wavelength and 150 fs temporal width ablation of As2S3 chalcogenide glasses is investigated by pump-probing technology. At lower laser fluence (8.26 mJ/cm2), the surface temperature dropping to the melting point is fast (about 43 ps), which results in a clean hole on the surface. As the laser fluence increases, it takes a longer time for lattice temperature to cool to the melting point at high fluence (about 200 ps for 18.58 mJ/cm2, about 400 ps for 30.98 mJ/cm2). The longer time of the surface heating temperature induces the melting pool in the center, and accelerates material diffusing and gathering surrounding the crater, resulting in the peripheral rim structure and droplet-like structure around the rim. In addition, the fabricated long periodic As2S3 glasses diffraction gratings can preserve with high diffraction efficiency by laser direct writing technology.
关键词： femtosecond laser,laser processing
更新于2025-09-11 14:15:04
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Femtosecond Laser Fabrication of Stable Hydrophilic and Anti-Corrosive Steel Surfaces
摘要： We report on a novel single-step method to develop steel surfaces with permanent highly hydrophilic and anti-corrosive properties, without employing any chemical coating. It is based on the femtosecond (fs) laser processing in a saturated background gas atmosphere. It is particularly shown that the fs laser microstructuring of steel in the presence of ammonia gas gives rise to pseudoperiodic arrays of microcones exhibiting highly hydrophilic properties, which are stable over time. This is in contrast to the conventional fs laser processing of steel in air, which always provides surfaces with progressively increasing hydrophobicity following irradiation. More importantly, the surfaces subjected to fs laser treatment in ammonia exhibit remarkable anti-corrosion properties, contrary to those processed in air, as well as untreated ones. The combination of two functionalities, namely hydrophilicity and corrosion resistance, together with the facile processing performed directly onto the steel surface, without the need to deposit any coating, opens the way for the laser-based production of high-performance steel components for a variety of applications, including mechanical parts, ?uidic components and consumer products.
关键词： femtosecond laser processing,wettability,steel,anticorrosion
更新于2025-09-11 14:15:04
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A review on glass welding by ultra-short laser pulses
摘要： Glass welding by ultra-short pulsed lasers is a piece of technology that offers high strength joints with hermetic sealing. The joints are typically formed in glass that is transparent to the laser by exploiting nonlinear absorption effects that occur under extreme conditions. Though the temperature reached during the process is on the order of a few 1000 °C, the heat affected zone (HAZ) is confined to only tens of micrometers. It is this controlled confinement of the HAZ during the joining process that makes this technology so appealing to a multitude of applications because it allows the foregoing of a subsequent tempering step that is typically essential in other glass joining techniques, thus making it possible to effectively join highly heat sensitive components. In this work we give an overview on the process, development and applications of glass welding by ultra-short pulsed lasers.
关键词： ultra-short pulsed laser processing,glass joining,USP glass welding,brittle materials
更新于2025-09-11 14:15:04
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Femtosecond Laser Processing and Evaluation of Broadband THz Anti-Reflection Structures
摘要： We fabricate terahertz anti-reflection structures on the surface of high-resistivity silicon via femtosecond laser processing. We measure its spectral properties by terahertz time-domain spectroscopy, and find a broadband increase in transmissivity over 0.3 - 2.5 THz. We investigate the observed spectral characteristics of this transmission by using numerical simulation. We successfully reproduce the observed result for all frequencies, including a previously undocumented high-frequency drop-off, when the model includes additional material losses. We believe these effects to be induced by the laser-ablation fabrication process.
关键词： anti-reflection,high-resistivity silicon,femtosecond laser processing,terahertz time-domain spectroscopy,terahertz
更新于2025-09-11 14:15:04
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Biocompatibility of micro/nanostructures nitinol surface via nanosecond laser circularly scanning
摘要： We present three novel scanning patterns on nitinol by nanosecond laser for controllable fabricating biocompatible micro/nanostructures. The surface morphology and formation mechanism of micro/nanostructures were respectively observed and analyzed. The production of surface oxide film provides a biocompatible cell living environment. Also, micro/nanostructures greatly promote cell adherence and growth. It is worth noting that ns laser circularly scanning can effortlessly produce various micro/nanostructures and endue biologically inert nitinol implants with enhanced osseointegration and bioactivity.
关键词： Microstructure,Nitinol,Laser processing,Surfaces,Biocompatibility
更新于2025-09-11 14:15:04
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Mechanical properties of Zr-based bulk metallic glass parts fabricated by laser-foil-printing additive manufacturing
摘要： The application of bulk metallic glasses (BMGs) has been traditionally limited to parts with small dimensions and simple geometries, due to the requirement of fast cooling during the conventional process of casting. This research exemplifies a promising additive manufacturing method, i.e., laser-foil-printing (LFP), to fabricate high-quality BMG parts with large dimensions and complex geometries. In this study, Zr52.5Ti5Al10Ni14.6Cu17.9 BMG parts were fabricated by LFP technology in which MG foils are laser welded layer-by-layer upon a substrate. The mechanical properties of the fabricated BMG parts were measured using micro-indentation, tensile test and four-point bending test, and compared to as-cast BMG parts. Through LFP, as rapid cooling rates can be achieved, fully amorphous and nearly fully dense BMG parts without cracking have been successfully made. The glass transition temperature, crystallization temperature, and melting temperature of the fabricated parts are nearly the same as those of the as-cast parts. Additionally, the fabricated BMG parts exhibit mechanical properties, including micro-hardness, tensile strength, and flexural strength, comparable to the as-cast BMG parts.
关键词： laser processing,additive manufacturing,bulk metallic glass,mechanical properties
更新于2025-09-09 09:28:46