Heat treatment behavior and strengthening mechanisms of CNT/6061Al composites fabricated by flake powder metallurgy
TL;DR: In this article, the carbon nanotubes reinforced 6061Al composites (CNT/6061Al) with CNTs uniformly dispersed were fabricated by flake powder metallurgy process.
About: This article is published in Materials Characterization.The article was published on 2019-07-01. It has received 28 citations till now. The article focuses on the topics: Strengthening mechanisms of materials & Ultimate tensile strength.
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TL;DR: A review of the tensile properties of carbon nanotube reinforced aluminium matrix (Al-CNT) composites can be found in this article, where various processing routes for fabrication of AlCNT composites have been compared in terms of the resulting microstructure, degree of CNT dispersion, extent of interfacial reaction and its effect on the tensil properties.
118 citations
TL;DR: In this paper, a powder assembly and alloying strategy was used to achieve trimodal grain structure in carbon nanotubes (CNTs) reinforced aluminum matrix composites.
Abstract: A novel strategy of powder assembly & alloying was used to achieve trimodal grain structure in carbon nanotubes (CNTs) reinforced aluminum matrix composites. The soft pure Al and hard 2024Al powders were firstly ball milled with CNTs for CNT/Al and CNT/2024Al flakes with different thicknesses, then were assembled with coarse-grained pure Al powders. Under the confinement of CNTs, these three building blocks evolved into ultrafine grains (UFG) smaller than 500 nm, fine grains (FG) between 500 nm and 2 μm and coarse grains (CG) about 9.8 μm, respectively, while the Al–Cu–Mg matrix achieved by the diffusion of Cu and Mg powders and elemental alloying with Al. Such a UFG-FG-CG trimodal grain structure contributed to superior strength-ductility synergy, as the 1.5 wt% CNT/Al–Cu–Mg composites exhibited tensile strength of 723 ± 6 MPa and elongation of 6.7 ± 0.6%. Therefore, powder assembly & alloying was proved an effective way to design and fabricate heterogeneous structured metal matrix nanocomposites.
24 citations
TL;DR: In this paper, an easy strategy was proposed to avoid and eliminate the negative effect of native oxide (Al2O3) layer by Mg addition, and significant improvement of ductility was achieved in the CNT/Al-Cu composite.
Abstract: The inevitable native oxide layer is a critical issue to achieve high mechanical performance of CNT/Al-alloy composites, especially prepared by powder metallurgy. Here, an easy strategy was proposed to avoid and eliminate the negative effect of native oxide (Al2O3) layer by Mg addition, and significant improvement of ductility was achieved in the CNT/Al-Cu composite. Native Al2O3 remained as continuous layers around CNTs or clusters of fragments in the CNT/Al-Cu without Mg addition. Mg addition transformed the native Al2O3 layer into spinel MgAl2O4 nano-phases dispersed both inside grains and on the interfaces. It is supposed that this transformation of oxide layer could improve the interfacial bonding due to Al-Al and Al-CNT direct interfacial contact. As a result, compared with CNT/Al-Cu composites, the tensile strength only changed a little, however, almost two times of fracture ductility was achieved by Mg addition in the final composites.
17 citations
TL;DR: In this article, a 5vol%SiC/AA2024 nanocomposite was prepared by a powder metallurgy routine involving high energy ball milling (HEBM), spark plasma sintering (SPS) and hot extrusion.
17 citations
10 Jun 2020-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, a modified powder metallurgy approach was used to construct a reinforced Al-Mg-Si composite, which had significantly higher uniaxial yield (236.2 ± 10.8 MPa) and tensile strengths (320.3 ± 4.0 MPa), but shared similar uniform elongation (9.8± 0.5 MPa).
Abstract: Bulk nanolaminated 0.4 wt% graphene (reduced graphene oxide, RGO)-reinforced Al–Mg–Si composite was fabricated using a modified powder metallurgy approach. The peakaged RGO-Al composite had significantly higher uniaxial yield (236.2 ± 10.8 MPa) and tensile strengths (320.3 ± 4.0 MPa), but shared similar uniform elongation (9.8 ± 0.5%) as compared to their unreinforced counterpart. These values are comparable or superior to the same series of alloys subject to complex thermo-mechanical treatments. Combining the mechanical test data with site-specific microstructural analysis, we rationalized the strength-ductility synergy in the composite by the refinement of the precipitates and the facilitated precipitation kinetics as a result of RGO incorporation, and the enhanced dislocation storage in the composite.
15 citations
References
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TL;DR: Although not yet providing compelling mechanical strength or electrical or thermal conductivities for many applications, CNT yarns and sheets already have promising performance for applications including supercapacitors, actuators, and lightweight electromagnetic shields.
Abstract: Worldwide commercial interest in carbon nanotubes (CNTs) is reflected in a production capacity that presently exceeds several thousand tons per year. Currently, bulk CNT powders are incorporated in diverse commercial products ranging from rechargeable batteries, automotive parts, and sporting goods to boat hulls and water filters. Advances in CNT synthesis, purification, and chemical modification are enabling integration of CNTs in thin-film electronics and large-area coatings. Although not yet providing compelling mechanical strength or electrical or thermal conductivities for many applications, CNT yarns and sheets already have promising performance for applications including supercapacitors, actuators, and lightweight electromagnetic shields.
4,596 citations
TL;DR: In this paper, a review summarises the research work carried out in the field of carbon nanotube (CNT) metal matrix composites (MMCs), focusing on the critical issues of CNT-reinforced MMCs that include processing techniques, nanotubes dispersion, interface, strengthening mechanisms and mechanical properties.
Abstract: This review summarises the research work carried out in the field of carbon nanotube (CNT) metal matrix composites (MMCs). Much research has been undertaken in utilising CNTs as reinforcement for composite material. However, CNT-reinforced MMCs have received the least attention. These composites are being projected for use in structural applications for their high specific strength as well as functional materials for their exciting thermal and electrical characteristics. The present review focuses on the critical issues of CNT-reinforced MMCs that include processing techniques, nanotube dispersion, interface, strengthening mechanisms and mechanical properties. Processing techniques used for synthesis of the composites have been critically reviewed with an objective to achieve homogeneous distribution of carbon nanotubes in the matrix. The mechanical property improvements achieved by addition of CNTs in various metal matrix systems are summarised. The factors determining strengthening achieved by CNT reinforcement are elucidated as are the structural and chemical stability of CNTs in different metal matrixes and the importance of the CNT/metal interface has been reviewed. The importance of CNT dispersion and its quantification is highlighted. Carbon nanotube reinforced MMCs as functional materials are summarised. Future work that needs attention is addressed.
1,265 citations
TL;DR: A heterogeneous lamella structure in Ti produced by asymmetric rolling and partial recrystallization that can produce an unprecedented property combination: as strong as ultrafine-grained metal and at the same time as ductile as conventional coarse- grained metal.
Abstract: Grain refinement can make conventional metals several times stronger, but this comes at dramatic loss of ductility. Here we report a heterogeneous lamella structure in Ti produced by asymmetric rolling and partial recrystallization that can produce an unprecedented property combination: as strong as ultrafine-grained metal and at the same time as ductile as conventional coarse-grained metal. It also has higher strain hardening than coarse-grained Ti, which was hitherto believed impossible. The heterogeneous lamella structure is characterized with soft micrograined lamellae embedded in hard ultrafine-grained lamella matrix. The unusual high strength is obtained with the assistance of high back stress developed from heterogeneous yielding, whereas the high ductility is attributed to back-stress hardening and dislocation hardening. The process discovered here is amenable to large-scale industrial production at low cost, and might be applicable to other metal systems.
1,063 citations
TL;DR: In this article, the authors focus on the recent development in the synthesis, property characterization and application of aluminum, magnesium, and transition metal-based composites reinforced with carbon nanotubes and graphene nanosheets.
Abstract: One-dimensional carbon nanotubes and two-dimensional graphene nanosheets with unique electrical, mechanical and thermal properties are attractive reinforcements for fabricating light weight, high strength and high performance metal-matrix composites. Rapid advances of nanotechnology in recent years enable the development of advanced metal matrix nanocomposites for structural engineering and functional device applications. This review focuses on the recent development in the synthesis, property characterization and application of aluminum, magnesium, and transition metal-based composites reinforced with carbon nanotubes and graphene nanosheets. These include processing strategies of carbonaceous nanomaterials and their composites, mechanical and tribological responses, corrosion, electrical and thermal properties as well as hydrogen storage and electrocatalytic behaviors. The effects of nanomaterial dispersion in the metal matrix and the formation of interfacial precipitates on these properties are also addressed. Particular attention is paid to the fundamentals and the structure–property relationships of such novel nanocomposites.
877 citations
TL;DR: In this article, three major mechanisms involved in CNT/Al composites are analyzed along with experimental procedure for making CNT and Al composites, along with three major composites strengthening mechanisms.
740 citations