Grain and nanoparticle coarsening of an ultrafine structured Cu–5vol.%Al2O3 nanocomposite during isochronal annealing

Zhou, Dengshan; Zhang, Deliang; Kong, Charlie; Munroe, Paul; Torrens, Rob

doi:10.1016/j.jallcom.2015.04.106

Cited by 26 publications

(3 citation statements)

References 40 publications

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“…In addition, the microhardness of the as-SPSed sample is similar to the microhardness of UFG Cu annealed at 673 K for 3 hours (69 HV), while the microhardness of the as-extruded sample is clearly higher than that UFG-Cu prepared by ECAP followed by annealing at 573 K for 10 hours (83.4 HV) 14 . The consistent and repeatable microhardness results as could be seen in Figure 6 described by Taylor's equation σ ∆ dis = M α Gb ρ 0.5 41 , where…”

Section: Mechanical Properties and Fracture Behaviorsupporting

confidence: 72%

Microstructure and Tensile Properties of Fine-Grained Bulk Copper Fabricated by Thermomechanical Consolidation of Copper Nanopowder/Micron-Sized Powder Blend

et al. 2022

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Samples of fine structured Cu were fabricated by spark plasma sintering (SPS) of compacts of Cu nanopowder/micron-sized powder blend with a ratio of 3:7 by weight, and one of the SPSed samples was further processed by hot extrusion. The microstructures of the as-SPSed and the as-extruded samples and the tensile properties and fracture behavior of the as-extruded sample were studied. It was found that the microstructures of the samples consist of a concoction of ultrafine and coarse grains with high dislocation densities ( ~1015 m -2 ) as a result of microstructural evolution during material processing. Some nanograins were oxidized to form Cu 2 O particles residing around the coarse grains. Extrusion of the SPSed sample increases its microhardness from 70 HV to 90 HV. The electrical conductivity of the as-extruded sample reaches 87% international annealed copper standard (IACS), and its tensile properties are 200 MPa for yield strength, 218 MPa for ultimate tensile strength and 9% for elongation to fracture. The tensile test specimens from the as-extruded sample exhibit nearly ideal plastic deformation and undergo ductile fracture, suggesting that the fine-grained copper is a highly desirable material for high strength electrical conductors.

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Section: Mechanical Properties and Fracture Behaviorsupporting

confidence: 72%

Microstructure and Tensile Properties of Fine-Grained Bulk Copper Fabricated by Thermomechanical Consolidation of Copper Nanopowder/Micron-Sized Powder Blend

et al. 2022

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“…Before hydrothermal annealing, the NPs have a calculated mean diameter of 3.2 ± 1.8 nm, which increases to 10.2 ± 1.6 nm following annealing. The similarity between the PXRD-determined crystallite size and the TEM-measured diameter of the NPs post-annealing indicates that the annealed NPs are single crystalline, whereas they were likely polycrystalline prior to the treatment [29,30]. It is, therefore, reasonable to conclude that the annealing treatment reduces grain boundaries within the as-prepared NPs, more so than it results in the ripening of the as-prepared NPs into larger particles.…”

Section: Synthesis and Impacts Of Hydrothermal Annealing On Crystallimentioning

confidence: 90%

Synthesis of Radioluminescent CaF2:Ln Core, Mesoporous Silica Shell Nanoparticles for Use in X-ray Based Theranostics

et al. 2020

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X-ray radiotherapy is a common method of treating cancerous tumors or other malignant lesions. The side effects of this treatment, however, can be deleterious to patient quality of life if critical tissues are affected. To potentially lower the effective doses of radiation and negative side-effects, new classes of nanoparticles are being developed to enhance reactive oxygen species production during irradiation. This report presents the synthesis and radiotherapeutic efficacy evaluation of a new nanoparticle formulation designed for this purpose, composed of a CaF2 core, mesoporous silica shell, and polyethylene glycol coating. The construct was additionally doped with Tb and Eu during the CaF2 core synthesis to prepare nanoparticles (NPs) with X-ray luminescent properties for potential application in fluorescence imaging. The mesoporous silica shell was added to provide the opportunity for small molecule loading, and the polyethylene glycol coating was added to impart aqueous solubility and biocompatibility. The potential of these nanomaterials to act as radiosensitizers for enhancing X-ray radiotherapy was supported by reactive oxygen species generation assays. Further, in vitro experiments indicate biocompatibility and enhanced cellular damage during X-ray radiotherapy.

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“…Previous studies [1,4,7,9,10] have shown the stability of microstructure and mechanical properties at elevated temperatures of Cu-Al2O3 composites. For instance, Xiang et al [1] have suggested that Cu-2.7 vol.% Al2O3 composite has high mechanical strength at elevated temperatures, which is attributed to the strong pinning effects of Al2O3 particles on the grain and sub-grain boundaries.…”

Section: Introduction mentioning

confidence: 97%

The Nanoparticle-induced Zener Pinning Effect on Strain-softening in a Cold-Worked Cu-Al2O3 Composite with 0.1 wt.% Al Content

ZHANG,

WEI,

et al. 2024

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The thermo-stability of microstructure during isothermal annealing at 900 °C and 1000 °C in a cold-worked Cu-Al2O3 composite with 0.1 wt.% Al content and its effect on resistance to softening were investigated in this paper. The results reveal that the microstructure following cold deformation consists of a Cu matrix with a refined grain size and high-density dislocations, accompanied by dispersed Al2O3 nanoparticles exhibiting an extremely low volume fraction. During isothermal annealing at 900 °C, the Al2O3 nanoparticles can strongly restrict the migration of the dislocations and suppress the recrystallization of the fine-grained Cu matrix by the Zener pinning effect. Furthermore, the presence of pinned dislocations facilitates the formation of sub-grain boundaries comprising high-density dislocations. Consequently, the Cu-Al2O3 composite with 0.1 wt.% Al content exhibits remarkable thermo-stability in its microstructure due to the incorporation of Al2O3 nanoparticles, resulting in a significantly elevated softening temperature of up to 1000 °C and thereby demonstrating excellent resistance against softening. However, the observed phenomenon of softening after isothermal annealing at 1000 °C for 5 hours can be attributed to extensive recrystallization growth that promotes twin boundary formation, primarily caused by the weakening Zener pinning effect resulting from Oswald ripening of Al2O3 and rod-like Al2O3 formation.

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Grain and nanoparticle coarsening of an ultrafine structured Cu–5vol.%Al2O3 nanocomposite during isochronal annealing

Cited by 26 publications

References 40 publications

Microstructure and Tensile Properties of Fine-Grained Bulk Copper Fabricated by Thermomechanical Consolidation of Copper Nanopowder/Micron-Sized Powder Blend

Microstructure and Tensile Properties of Fine-Grained Bulk Copper Fabricated by Thermomechanical Consolidation of Copper Nanopowder/Micron-Sized Powder Blend

Synthesis of Radioluminescent CaF2:Ln Core, Mesoporous Silica Shell Nanoparticles for Use in X-ray Based Theranostics

The Nanoparticle-induced Zener Pinning Effect on Strain-softening in a Cold-Worked Cu-Al2O3 Composite with 0.1 wt.% Al Content

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