Effects of particle reinforcement and ECAP on the precipitation kinetics of an Al-Cu alloy

Härtel, M.; Wagner, S.; Frint, Philipp; Wagner, Martin F.-X.

doi:10.1088/1757-899x/63/1/012080

Cited by 18 publications

(20 citation statements)

References 16 publications

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“…Hence, an initial concentration of defects introduced by either quenching or by early plastic deformation is required to increase diffusion rates of the solute atoms and thus to trigger dislocation pinning. As discussed in [14,48], an earlier occurrence of stress serrations in the particle reinforced material ( Figure 3) is in good agreement with this interpretation: The particle/matrix interfaces and the stress fields surrounding the particles locally lead to a rapid increase of the dislocation density [33] during plastic deformation. This increased number of defects allows for faster pipe diffusion processes [54][55][56][57] and-for the material studied here-accelerates dynamic strain aging at lower strain values.…”

Section: Introductionsupporting

confidence: 81%

On the PLC Effect in a Particle Reinforced AA2017 Alloy

Härtel¹,

Illgen²,

Frint³

et al. 2018

Metals

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Abstract:The Portevin-Le Châtelier (PLC) effect often results in serrated plastic flow during tensile testing of aluminum alloys. Its magnitude and characteristics are often sensitive to a material's heat treatment condition and to the applied strain rate and deformation temperature. In this study, we analyze the plastic deformation behavior of an age-hardenable Al-Cu alloy (AA2017) and of a particle reinforced AA2017 alloy (10 vol. % SiC) in two different conditions: solid solution annealed (W) and naturally aged (T4). For the W-condition of both materials, pronounced serrated flow is observed, while both T4-conditions do not show distinct serrations. It is also found that a reduction of the testing temperature (−60 • C, −196 • C) shifts the onset of serrations to larger plastic strains and additionally reduces their amplitude. Furthermore, compressive jump tests (with alternating strain rates) at room temperature confirm a negative strain rate sensitivity for the W-condition. The occurring PLC effect, as well as the propagation of the corresponding PLC bands in the W-condition, is finally characterized by digital image correlation (DIC) and by acoustic emission measurements during tensile testing. The formation of PLC bands in the reinforced material is accompanied by distinct stress drops as well as by perceptible acoustic emission, and the experimental results clearly show that only type A PLC bands occur during testing at room temperature (RT).

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Section: Introductionsupporting

confidence: 81%

On the PLC Effect in a Particle Reinforced AA2017 Alloy

Härtel¹,

Illgen²,

Frint³

et al. 2018

Metals

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“…, [9] we have documented that the precipitation kinetics after one pass of ECAP are accelerated and that the early formation of precipitates is shifted toward lower temperatures. This can be related to faster diffusion promoted by larger numbers of vacancies, [21] dislocations, and grain boundaries.…”

Section: Methodsmentioning

confidence: 80%

“…The sample shown in Figure 1b was heated up to 270 C and quenched immediately thereafter. [9] For that material condition, fine u 0 precipitates can also be observed. In ref.…”

Section: Methodsmentioning

confidence: 85%

“…This can be related to faster diffusion promoted by larger numbers of vacancies, [21] dislocations, and grain boundaries. [9] Especially, the larger number of dislocations can be observed in the microstructure after one pass of ECAP (Figure 1c). The increased number of dislocations is also an indication that the ECAP deformation temperature is not too high and does not prevent severe plastic deformation processes (formation of cell and low angle grain boundaries).…”

Section: Methodsmentioning

confidence: 93%

“…[2][3][4] The microstructure after SPD processing is often heterogeneous and meta-stable [5][6][7] : the long-term mechanical properties may, therefore, change at elevated temperatures. Moreover, recent studies have highlighted that both creep testing [8] and SPD processes (like ECAP [9,10] or high pressure torsion [5] ) lead to an acceleration of the precipitation kinetics of Al-Cu alloys. It is, however, not known how a combination of bothcreep straining of ECAP-deformed Al-Cu alloys -can affect the precipitation kinetics.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Creep and Aging on the Precipitation Kinetics of an Al–Cu Alloy after One Pass of ECAP

et al. 2017

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Recent work shows that severe plastic deformation processes such as ECAP or HPT considerably accelerate the precipitation kinetics of Al-Cu alloys. In this study, the authors analyze how a combination of mechanical load, aging time (and increased plastic strain), and aging temperature affects the precipitation kinetics of an AA2017 alloy after ECAP. After solution annealing, the material is processed by one pass of ECAP (120 -channel angle) at 140 C. Compressive creep tests are performed on the initial condition and the ECAP-deformed material. The resulting microstructures are studied in detail using electron microscopy. To investigate the influence of mechanical loading, interrupted compressive creep tests are performed and compared with aged samples (produced without any mechanical loading at the same temperature and after the same amount of time). By keeping time and load constant in another set of interrupted compressive creep tests, the influence of temperature is investigated. Our study shows that increasing mechanical loading further accelerates the precipitation kinetics. Temperature accelerates the precipitation kinetics as well, but results in coarser precipitates. The authors also find that different creep strains can lead to the formation of two different regions in the microstructure: regions with only a few coarsened uphase precipitates, and regions with numerous, finely dispersed precipitates.

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