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In vitro bioactivity and biocompatibility of femtosecond laser-modified Ti6Al4V alloy
摘要： The present work investigates bioactivity and biocompatibility of femtosecond (fs) laser surface-modified Ti6Al4V alloy (Ti-alloy). Self-aligned conical surface features were generated on Ti-alloy when laser irradiated employing a Ti:sapphire pulsed fs laser of wavelength 800 nm. Modification of surface chemical composition resulting from fs-laser irradiation of Ti-alloy was examined using Grazing incidence X-ray diffraction (GIXRD) technique and micro-Raman spectroscopy. Sub-oxide phase of titanium was detected on Ti-alloy surface post-fs-laser irradiation leading to increased oxygen vacancies on sample surface. For in vitro bioactivity tests, untreated and fs-laser-treated samples were immersed in simulated body fluid for 2 weeks. Evidence of hydroxyapatite deposition on both untreated Ti-alloy, as well as, fs-laser-treated Ti-alloy surfaces after in vitro tests were provided by scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), GIXRD, Fourier transform infrared spectroscopy (FTIR), and micro-Raman spectroscopy. Superior growth of HAP was observed on fs-laser-modified Ti-alloy surface in comparison with untreated surface. Biocompatibility of the laser-treated Ti-alloy was investigated by studying anchoring and growth of human osteosarcoma cell line (U2OS) on it. Using MTT assay technique in vitro cell viability and growth potential in the presence of untreated and laser-treated Ti-alloy samples were assessed. MTT test results demonstrated that, neither cell viability, nor growth were affected in the presence of either the untreated or laser-treated sample surfaces. In addition, in comparison with the untreated Ti-alloy surface, the fs-laser-treated Ti-alloy surface showed more efficient cellular attachment when examined under confocal microscope.
关键词： Biocompatibility,Hydroxyapatite,Surface modification,Ti6Al4V alloy,Femtosecond laser,Bioactivity
更新于2025-11-21 11:08:12
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Rapid Alloy Development of Extremely High-Alloyed Metals Using Powder Blends in Laser Powder Bed Fusion
摘要： The design of new alloys by and for metal additive manufacturing (AM) is an emerging field of research. Currently, pre-alloyed powders are used in metal AM, which are expensive and inflexible in terms of varying chemical composition. The present study describes the adaption of rapid alloy development in laser powder bed fusion (LPBF) by using elemental powder blends. This enables an agile and resource-efficient approach to designing and screening new alloys through fast generation of alloys with varying chemical compositions. This method was evaluated on the new and chemically complex materials group of multi-principal element alloys (MPEAs), also known as high-entropy alloys (HEAs). MPEAs constitute ideal candidates for the introduced methodology due to the large space for possible alloys. First, process parameters for LPBF with powder blends containing at least five different elemental powders were developed. Secondly, the influence of processing parameters and the resulting energy density input on the homogeneity of the manufactured parts were investigated. Microstructural characterization was carried out by optical microscopy, electron backscatter diffraction (EBSD), and energy-dispersive X-ray spectroscopy (EDS), while mechanical properties were evaluated using tensile testing. Finally, the applicability of powder blends in LPBF was demonstrated through the manufacture of geometrically complex lattice structures with energy absorption functionality.
关键词： multi-principal element alloys,high-entropy alloys,additive manufacturing,rapid alloy development,powder blends,laser powder bed fusion
更新于2025-11-21 11:01:37
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Precipitation behavior of selective laser melted FeCoCrNiC0.05 high entropy alloy
摘要： Interstitial elements are e?ective to strengthen high entropy alloys (HEAs). In this work, FeCoCrNiC0.05 was prepared by selective laser melting (SLM) followed by annealing. The e?ects of annealing on the microstructures and mechanical properties of the SLMed FeCoCrNiC0.05 were investigated. Results show that, nano-scale Cr23C6-type carbides can precipitate under annealing conditions, leading to higher yielding strength. The SLMed FeCoCrNiC0.05 annealed at 1073 K for 0.5 h has a yielding strength of 787 MPa and an elongation of 10.3%. Precipitation kinetics in SLMed FeCoCrNiC0.05 has been established according to Avrami formula. The high strength can be attributed to solid solution hardening, precipitation hardening and cell-like structures.
关键词： Precipitation kinetics,Hardening mechanism,Selective laser melting,Mechanical properties,High entropy alloy
更新于2025-11-14 17:04:02
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Microstructure and properties of laser interference crystallized amorphous FeSiB ribbon
摘要： The influence of Q-switched pulsed Nd:YAG laser interference heating, using 120 mJ of pulse energy and a variable number of consecutive pulses, on the microstructure and magnetic properties of amorphous Fe80Si11B9 alloy was examined. Microstructural analysis, using light, scanning and transmission electron microscopy, was complemented by results of M?ssbauer spectroscopy and measurement of magnetic properties (vibrating sample magnetometer). Periodically distributed crystallized micro-areas, *10 lm in diameter, in an amorphous matrix were produced by the treatments. Magnetization measurements showed that the as-cast ribbon and laser light irradiated samples are magnetically soft materials. The results lead to the conclusion that the dots corresponding to the laser modified regions exhibit a perpendicular magnetic anisotropy.
关键词： Laser interference heating,SEM,TEM,FeSiB amorphous alloy,Magnetic properties
更新于2025-11-14 17:04:02
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Synthesis of CoNi bimetallic alloy nanoparticles wrapped in nitrogen-doped graphite-like carbon shells and their electrocatalytic activity when used in a counter electrode for dye-sensitized solar cells
摘要： Nanoparticles of the bimetallic alloy CoNi wrapped in nitrogen-doped graphite-like carbon shells and dispersed on nitrogen-doped graphite-like carbon sheets (CoxNi1?x@NC) were synthesized by calcining CoNi metal–organic frameworks that were prepared through a facile solvothermal reaction using various raw-material molar ratios Co:Ni and CoNi:ethylenedinitrilotetraacetic acid. After depositing CoxNi1?x@NC for use as a counter electrode film in dye-sensitized solar cells, it was found that the electrocatalytic activity of the CoxNi1?x@NC counter electrode towards triiodide reduction could be optimized by simply tuning the molar ratios (Co:Ni and CoNi:ethylenedinitrilotetraacetic acid) appropriately during CoxNi1?x@NC synthesis. Cells that utilized a CoxNi1?x@NC counter electrode exhibited strong chemical-composition-dependent photovoltaic performance. Under optimal conditions, the CoxNi1?x@NC counter electrode presented an impressive energy conversion efficiency of 3.58%, suggesting that it is a highly promising counter electrode for application in dye-sensitized solar cells. This counter electrode has the advantages that it is considerably less expensive than a Pt counter electrode and that it provides the basis for the design and preparation of other inexpensive and efficient counter electrodes to replace Pt.
关键词： Photovoltaic performance,Dye-sensitized solar cells,CoNi alloy bimetallic nanoparticles,Counter electrode,Electrocatalytic activity
更新于2025-11-14 17:04:02
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Influence of multiple laser peening on vibration fatigue properties of TC6 titanium alloy
摘要： In this study, typical TC6 titanium alloy was taken to investigate the effects of multiple laser peening (LP) on the vibration fatigue properties and microstructural evolution. The vibration fatigue experiments were conducted, while the vibration fatigue life of the specimens before and after LP was compared and the fracture morphologies were observed by scanning electron microscopy (SEM). In addition, the measurements of residual stress and microhardness were carried out. The microstructures produced by different treatments were also characterized by transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD). The experimental results indicated that multiple LP could indeed enhance the vibration fatigue properties of TC6 titanium alloy. Comparing with the investigated specimen without LP, the vibration fatigue life of the specimen subjected to 5 times LP increased by 105.2%. Meanwhile, after 5 times LP, the surface residual stress transformed from tensile stress (+26 MPa) to compressive stress (?485 MPa), and the surface microhardness was 428 HV, which increased by 32.9% compared with the untreated sample. Additionally, high-density of dislocation and deformation twin were also generated after multiple LP. The improvement of vibration fatigue properties was attributed to the rewarding compressive residual stress and the beneficial microstructural evolution induced by multiple LP.
关键词： TC6 titanium alloy,Laser peening,Vibration fatigue properties,Microstructure evolution,Residual stress
更新于2025-11-14 17:04:02
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Novel PtPd alloy nanoparticle-decorated g-C3N4 nanosheets with enhanced photocatalytic activity for H2 evolution under visible light irradiation
摘要： PtPd bimetallic alloy nanoparticle (NP)-modified graphitic carbon nitride (g-C3N4) nanosheet photocatalysts were synthesized via chemical deposition precipitation. Characterization of the photocatalytic H2 evolution of the g-C3N4 nanosheets shows that it was significantly enhanced when PtPd alloy NPs were introduced as a co-catalyst. The 0.2 wt% PtPd/g-C3N4 composite photocatalyst gave a maximum H2 production rate of 1600.8 μmol g–1 h–1. Furthermore, when K2HPO4 was added to the reaction system, the H2 production rate increased to 2885.0 μmol g–1 h–1. The PtPd/g-C3N4 photocatalyst showed satisfactory photocatalytic stability and was able to maintain most of its photocatalytic activity after four experimental photocatalytic cycles. In addition, a possible mechanism for the enhanced photocatalytic activity was proposed and verified by various photoelectric techniques. These results demonstrate that the synergistic effect between PtPd and g-C3N4 helps to greatly improve the photocatalytic activity of the composite photocatalyst.
关键词： H2 evolution,PtPd alloy nanoparticles,Photocatalysis,g-C3N4 nanosheets
更新于2025-11-14 17:03:37
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Plastic anisotropy of laser melting deposited Ti–5Al–5Mo–5V–1Cr–1Fe titanium alloy
摘要： Tensile tests of laser melting deposited Ti–5Al–5Mo–5V–1Cr–1Fe titanium alloy specimens in different orientations were conducted, which indicates significant plastic anisotropy of this material. Digital image correlation method added in-situ-tensile tests were carried out to investigate mechanical properties with respect to specified material structures. The results indicate that the plasticity properties of the thick columnar grain and that of other grains are significant different. Under the same stress level, the thick columnar grain yield firstly and bear the main plastic deformation of the whole specimen. The elasto-plastic Poisson's ratio of the thick columnar grains and that of other grains are also different. Tests on layer bands indicate that the coarser microstructures of the layer bands lead a stronger resistance to tensile plastic deformation, but a weaker resistance to shear plastic deformation. In addition, the direction of primary α laths on both sides of the layer bands may be different, and this has an obviously effect on the tensile plastic deformation of the specimen.
关键词： Digital image correlation method,Plastic anisotropy,Laser melting deposited,Titanium alloy,Mechanical properties
更新于2025-10-24 16:40:20
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Hole Blocking Layer-Free Perovskite Solar Cells with High Efficiencies and Stabilities by Integrating Subwavelength-Sized Plasmonic Alloy Nanoparticles
摘要： Perovskite solar cells hold great promise as prospective alternatives of renewable power sources. Recently hole blocking layer-free perovskite solar cells, getting rid of complex and high-temperature fabrication processes, have engaged in innovative designs of photovoltaic devices. However, the elimination of the hole blocking layer constrains the energy conversion efficiencies of perovskite solar cells, and severely degrades the stabilities. In this paper a simple approach (without energy-consuming and time-consuming procedures) for the fabrication of hole blocking layer-free perovskite solar cells has been demonstrated by an integration of copper-silver alloy nanoparticles, which are synthesized by wet chemical method with controllable diameters and elemental compositions. The rear-side integration of the subwavelength-sized silver-copper alloy particles (200 nm diameter), through a spraying/drying method, realizes a pronounced absorption enhancement of the perovskite layer by effectively light scattering in a broadband wavelength range, and achieves a series resistance decrease of the solar cell due to high electrical conductivities of the alloy particles. The particle integration achieves the highest efficiency of 18.89% due to the significant improvement in both optical and electrical properties of solar cells, making this device one of the highest-performing blocking layer-free perovskite solar cells and plasmonic perovskite solar cells. Moreover, the copper-based nanoparticles prevent the perovskite from diffusing into metal back electrodes. Because the diffusion can lead to a severe corrosion of the Au electrode and thus an efficiency degradation, the alloy nanoparticle integration between the perovskite and the electrode results in 80% and 200% improvements in the long-term stability and the photostability of solar cells, respectively. Through the proposed simple and effective fabrication process, our results open up new opportunities in the manufacturability of perovskite solar cells.
关键词： light scattering,Perovskite solar cells,plasmonic,subwavelength-sized,alloy,hole blocking layer,stability
更新于2025-10-22 19:40:53
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Effects of coverage layer on the electrochemical corrosion behaviour of Mg-Al-Mn alloy subjected to massive laser shock peening treatment
摘要： Effects of coverage layer on electrochemical corrosion behaviour and pitting morphologies of Mg-Al-Mn alloy subjected to massive laser shock peening (LSP) treatment were investigated by potentiodynamic polarisation test, electrochemical impedance spectroscopy (EIS), and scanning electron microscope (SEM) observations. Microstructures of Mg-Al-Mn alloy subjected to massive LSP treatment were also characterized. Results showed that LSP induced an obvious improvement in electrochemical corrosion resistance with increasing coverage layer. Even in a higher corrosive solution concentration, LSP could still prevent corrosion to some extent. The improvement in electrochemical corrosion resistance was due to the grain refinement and compressive residual stress induced by massive LSP treatment. Finally, the influence mechanism of the coverage layer on electrochemical corrosion behavior of Mg-Al-Mn alloy was revealed.
关键词： Microstructure.,Electrochemical corrosion,Mg-Al-Mn alloy,Coverage layer,Laser shock peening
更新于2025-09-23 15:23:52