Modelling of Creep in Alloys Strengthened by Rod-Shaped Particles: Al-Cu-Mg Age-Hardenable Alloys

Precipitation-hardened AlSi 356 cast alloys are widely used in fabricating the automotive engine parts due to their excellent castability and strength/weight ratio. However, with the increasing demand of the engine service temperature at 250350°C, the mechanical properties of AlSi 356 alloys greatly deteriorate owing to the rapid coarsening of precipitates at elevated temperatures. In this study, individual and combined transition elements (V, Zr and Mo) were introduced into AlSi 356 type cast alloys to form thermally stable dispersoids, and their influences on the strength and creep resistance at 300°C was investigated. During thermal exposure (300°C/100 h) after T7 treatment, the nano-scale ¢A and QA precipitated during aging were transformed to the equilibrium coarse ¢ and Q phases, loosing their contribution to mechanical strength. However, different types of dispersoids formed during the solution treatment were stable during the thermal exposure, resulting in the different but promising contribution to the elevated-temperature properties. The combined additions of V, Zr and Mo showed the highest mechanical and second highest creep properties at 300°C, which possess 22% and 100% improvement on the strength and creep resistance compared to the base alloy.

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“…As reported in Ref. 27) that the spherical particles can lower the minimum creep rate than the rod-like ones. As shown in Fig.…”

Section: Discussionmentioning

confidence: 53%

Evolution of Microstructure and Elevated-Temperature Properties during Thermal Exposure with Transition Elements (V, Zr and Mo) in Al–Si 356 Type Cast Alloys

Liu

Chen

2023

Mater. Trans.

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“…Al-Cu and Al-Cu-Mg alloys are widely used in the aircraft industry due to their excellent mechanical properties, which depend on the fine dispersion of secondary phase strengthening precipitates [1][2][3][4].…”

Section: Introductionmentioning

confidence: 99%

High-Temperature Equal-Channel Angular Pressing of a T6-Al-Cu-Li-Mg-Ag-Zr-Sc Alloy

Cabibbo

Paoletti

2021

JMMP

Self Cite

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Equal-channel angular pressing (ECAP) is known to induce significant grain refinement and formation of tangled dislocations within the grains. These are induced to evolve to form low-angle boundaries (i.e., cell boundaries) and eventually high-angle boundaries (i.e., grain boundaries). On the other hand, the precipitation sequence of age hardening aluminum alloys can be significantly affected by pre-straining and severe plastic deformation. Thus, ECAP is expected to influence the T6 response of aluminum alloys. In this study, a complex Al-Cu-Mg-Li-Ag-Zr-Sc alloy was subjected to ECAP following different straining paths. The alloy was ECAP at 460 K via route A, C, and by forward-backward route A (FB-route A) up to four passes. That is, ECAP was carried out imposing billet rotation between passes (route A), billet rotation by +90° between passes (route C), and billet rotation by +90° and inversion upside down between passes (FB-route A). The alloy was also aged at 460 K for different durations after ECAP. TEM microstructure inspections showed a marked influence of the different shearing deformations induced by ECAP on the alloy aging response. The precipitation kinetics of the different hardening secondary phases were affected by shearing deformation and tangled dislocations. In particular, the T1-Al2CuLi phase was the one that mostly showed a precipitation sequence speed up induced by the tangled dislocations formed during ECAP. The T1 phase was found to grow with aging time according to the Lifshitz-Slyozov-Wagner low-power regime.

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“…Song et al [21] found that the dimensional stability of an Al-Cu-Mg alloy can be improved by stress-aging. Paoletti et al [22] and Li et al [23] modeled the creep behavior of an aged Al-Cu-Mg alloy. Li et al [24] discussed the synergy influence of pre-straining and Si addition on microstructures of Al-Cu-Mg alloys.…”

Section: Introductionmentioning

confidence: 99%

Deformation Behavior and Precipitation Features in a Stretched Al–Cu Alloy at Intermediate Temperatures

et al. 2020

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Deformation behavior and precipitation features of an Al–Cu alloy are investigated using uniaxial tensile tests at intermediate temperatures. It is found that the true stress drops with the decreased strain rate or the increased deformation temperature. The number of substructures and the degree of grain elongation decrease with the raised temperature or the decreased strain rate. At high temperatures or low strain rates, some dynamic recrystallized grains can be found. The type of precipitates is influenced by the heating process before hot tensile deformation. The content and size of precipitates increase during tensile deformation at intermediate temperatures. As the temperature increases over 200 °C, the precipitation process (Guinier Preston zone (G.P. zones)→θ′′ phase→θ′ phase) is enhanced, resulting in increased contents of θ′′ and θ′ phases. However, θ′′ and θ′ phases prefer to precipitate along the {020}Al direction, resulting in an uneven distribution of phases. Considering the flow softening degree and the excessive heterogeneous precipitation of θ′′ and θ′ phases during hot deformation, the reasonable strain rate and temperature are about 0.0003 s−1 and 150 °C, respectively.

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Modelling of Creep in Alloys Strengthened by Rod-Shaped Particles: Al-Cu-Mg Age-Hardenable Alloys

Cited by 10 publications

References 41 publications

Evolution of Microstructure and Elevated-Temperature Properties during Thermal Exposure with Transition Elements (V, Zr and Mo) in Al–Si 356 Type Cast Alloys

Evolution of Microstructure and Elevated-Temperature Properties during Thermal Exposure with Transition Elements (V, Zr and Mo) in Al–Si 356 Type Cast Alloys

High-Temperature Equal-Channel Angular Pressing of a T6-Al-Cu-Li-Mg-Ag-Zr-Sc Alloy

Deformation Behavior and Precipitation Features in a Stretched Al–Cu Alloy at Intermediate Temperatures

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