Investigation of Microstructures and Mechanical Properties of SiC/AA2024 Nanocomposites Processed by Powder Metallurgy and T6 Heat Treatment

Abstract

SiC/AA2024 nanocomposites with 1 and 5 vol.% SiC nanoparticles have been prepared by a powder metallurgy route involving high-energy ball-milling (HEBM), spark plasma sintering (SPS), and hot extrusion. The microstructures and mechanical properties of the nanocomposite samples before and after T6 heat treatment were investigated. The samples exhibited a bimodal microstructure with SiC nanoparticles being dispersed in it. With increasing the SiC nanoparticle content from 1 to 5 vol.%, the yield strength (YS) and ultimate tensile strength (UTS) increased and the elongation to fracture (El) slightly decreased. After T6 heat treatment, a simultaneous improvement of the strength and ductility was observed, with the YS, UTS, and El increasing from 413 MPa, 501 MPa, and 5.4% to 496 MPa, 572 MPa, and 6.7%, respectively, in the 1 vol.%SiC/AA2024 nanocomposite sample. Analysis of the deformation behavior shows that this improvement is likely caused by the increased density of geometrically necessary dislocations (GNDs) resulting from the bimodal microstructure. The dispersed intragranular Sʹ precipitates generated by the T6 heat treatment also make a contribution to the increase of strength and ductility by accumulating dislocations. It is feasible to realize simultaneous improvement of strength and ductility in the SiC/AA2024 nanocomposites via powder metallurgy and subsequent heat treatment.

Research progress on ceramic nanomaterials reinforced aluminum matrix nanocomposites

“…Sintering process will help for bonding ceramic nanoparticles with aluminium matrix. Mu et al [73] reported aluminium matrix nanocomposites reinforced with SiC nanomaterial and produced by powder metallurgy method. The process has been schematically shown in Figure 4.…”

“…Afterwards, powder has been consolidated by spark plasma sintering process at 500°C for 10 min under 50 MPa pressure. Afterwards, samples were hot extruded at extrusion ration of 16:1 under the flow of argon gas [73]. Microstructure and properties of metal matrix nanocomposites were influenced by process parameters in powder metallurgy method [74].…”

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Figure 4 Schematic showing steps for powder metallurgy route to fabricate ceramic nanoparticles reinforced aluminium matrix nanocomposite: (a) high energy ball milling process; (b) spark plasma sintering process and (c) hot extrusion of sample. Reproduced from ref [73] © 2022 by the authors (Open access).

Figure 5 Optical microscopic images of pure AA7075 (a), and 0.5 wt% of Y 2 O 3 nanoparticle reinforced aluminium matrix nanocomposites processed at milling time of (b) 0.25 h, (c) 1 h, (d) 2 h, (e) 2 h and (f) 10 h.

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“…Schematic showing steps for powder metallurgy route to fabricate ceramic nanoparticles reinforced aluminium matrix nanocomposite: (a) high energy ball milling process; (b) spark plasma sintering process and (c) hot extrusion of sample. Reproduced from ref [73] © 2022 by the authors (Open access).…”