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Atomic structure revolution and excellent performance improvement of composites induced by laser ultrafine-nano technology
摘要： Carbon nanotubes (CNTs) reinforced high-entropy alloy composites (HEACs) were fabricated on a TA2 titanium alloy by mean of a laser melting deposition (LMD) of the FeCoCrAlCu-(nano-SiB6)-(Ni/Ag-coated CNTs) mixed powders, noting that large quantities of the ultrafine nanocrystals (UNs) were formed, portion of them were able to obtain the enormous energy from laser beam, which were able to permeate into the original ordered atom arrangement due to the high diffusion rates and their ultrafine microstructure. In substance, partial UNs can destroy the balanced state of atoms, increasing significantly the free energy of the crystal boundaries. Such CNTs/UNs modified LMD composites showed the better corrosion/high-temperature oxidation resistance properties than those of the TA2 alloy. Identification of the synthetic UNs in such LMD HEACs, more importantly the UNs transition effect, contributes theoretical/experimental basis to upgrade the quality of the industrial light alloy.
关键词： Metal-matrix composites (MMCs),Surface treatments,Laser melting deposition,Nanocomposites,Powder processing
更新于2025-09-16 10:30:52
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Effect of powder characteristics on production of oxide dispersion strengthened Fe 14Cr steel by laser powder bed fusion
摘要： In order to assess the potentialities of additive manufacturing in nuclear industry, Oxide Dispersion Strengthened (ODS) Fe\14Cr steels are produced by laser powder bed fusion (L-PBF). Such materials are currently manufactured by milling a Fe\14Cr atomized powder with Y2O3 and TiH2 powders. The resulting powder has a non-spherical shape being coarser than powders typically used in L-PBF equipment. The influence of powder characteristics on the processability of ODS Fe\14Cr by L-PBF are studied in details. Four different powders are used. These powders differ from size, morphology and chemical composition. Finer is the powder; wider is the process range to obtain dense samples. This phenomenon could be mitigated by transferring an amount of energy superior to 110 J.mm?3. The presence of yttrium and titanium gives columnar microstructure for ODS samples, whereas Fe\14Cr samples have stirred microstructure. Titanium and yttrium form oxides, which enlarge the melt pool and induce columnar growth.
关键词： Additive manufacturing,Powder flowability,Metal Matrix Composites (MMCs),Chemical composition,Laser Powder Bed Fusion (L-PBF),Particle size distribution
更新于2025-09-11 14:15:04
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Laser additive manufacturing of nano-TiC reinforced Ni-based nanocomposites with tailored microstructure and performance
摘要： Laser additive manufacturing has demonstrated a promising capability in the simultaneous formation of high-performance nanocomposites with unique microstructure characteristics. The present work studied the densification, microstructure and mechanical properties of nano-TiC reinforced Inconel 718 composites processed by selective laser melting (SLM) with variation of laser energy linear density (E). It revealed that a fully dense TiC/Inconel 718 part was fabricated at a proper E of 300 J/m. On increasing E from 225 to 300 J/m, the nano-TiC reinforcement experienced severe agglomeration to uniform distribution along the grain boundaries and inside the grains of matrix. The morphologies of nano-particles transferred from irregular polygonal to near-spherical shape. The presence of nano-TiC could also accelerate the refinement of columnar dendrites spacing of γ matrix. A high nanohardness of 4.48 GPa, a low coefficient of friction of 0.36 and resultant low wear rate of 3.83 × 10?4 mm3/N?m were obtained at E of 300 J/m, showing a significantly improved mechanical performance compared to the SLM-processed unreinforced nickel-based alloys.
关键词： Nano-TiC,Metal-matrix composites (MMCs),Selective laser melting,Microstructures,Mechanical properties
更新于2025-09-11 14:15:04