Modeling age hardening kinetics of an Al–Mg–Si–Cu aluminum alloy

Eivani, A.R.; Taheri, Ali

doi:10.1016/j.jmatprotec.2007.11.195

Cited by 34 publications

(8 citation statements)

References 17 publications

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“…The ageing behaviour of Al-Mg-Si alloys has been widely studied, and the precipitation evolution sequence of an as-quenched alloy with the supersaturated solid solution (SSSS) condition can be summarised as [12][13][14]:…”

Section: Introductionmentioning

confidence: 99%

Experimental investigations of stress-relaxation ageing behaviour of AA6082

Rong

Shi

et al. 2019

Materials Science and Engineering: A

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Stress-relaxation ageing behaviour of peak-aged aluminium alloy 6082 (AA6082-T6) has been experimentally investigated with initial loading in both elastic and plastic regions in this study. The stress-relaxation ageing tests with various initial strain levels were carried out at 160 °C for up to 12 hrs and room temperature tensile tests were performed subsequently. Selected samples have been examined using transmission electron microscopy (TEM) to study microstructural evolution during the process. The results show that the total stress relaxed after 12 hr test increases significantly with increasing initial strain levels. The initial strain levels contribute little effect on yield strength evolution during stress-relaxation ageing, as softening from the coarsening of ′′ precipitates is balanced by hardening from dislocations. Stressrelaxation mechanisms of the material have been analysed on the basis of creep stress exponent. In the elastic region, a creep stress exponent of 3 with a threshold stress of 70.1 MPa has been obtained, indicating a dislocation glide controlled creep mechanism; while in the plastic region, a decreasing threshold stress with increasing initial strain levels has been proposed to achieve a positive creep stress exponent.

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Section: Introductionmentioning

confidence: 99%

Experimental investigations of stress-relaxation ageing behaviour of AA6082

Rong

Shi

et al. 2019

Materials Science and Engineering: A

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“…Secondly, the alloy hardness raises first (under-aged state), and then decreases (over-aged state) during the aging process. The hardness increment is attribute to the formation of nano-sized θ′ precipitates [ 37 ]. Clearly, the higher aging temperature has corresponded to the more obvious hardness reduction after the PA point at the over-aged stage ( Figure 2 a).…”

Section: Resultsmentioning

confidence: 99%

Morphological Evolutions of Ni-Rich Phases in Al-Si Piston Alloys during 250–400 °C Thermal Exposure Processes

Geng

Bian

et al. 2020

Materials

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The thermal stability of the Al-Si alloys during the thermal exposure process from 250 °C to 400 °C was systematically investigated. The relationships between the morphological evolution and the mechanical changes of the alloys were determined through the Vickers hardness test and materials characterization method. Initially, the alloys exhibited similar thermal degradation behavior. For example, the exposure process of the alloy at 300 °C can be divided into two stages according to the changes of the alloy hardness and the matrix micro-hardness. In detail, the first stage (0–2 h) exhibited a severe reduction of the alloy hardness while the second stage showed a more leveled hardness during the following 98 h. There are three identified morphological characteristics of Ni-rich phases in the alloy. Furthermore, the differences in both composition and the micro-hardness between these Ni-rich phases were confirmed. The underlying relationships between the morphological transformation of the Ni-rich phases and hardness fluctuation in the alloy were correlated and elucidated. The observed alloy hardness increase when the exposure temperature was 400 °C was unexpected. This behavior was explained from the perspectives of both Ni-rich phases evolution and dispersoid formation.

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“…[19] The early stages of hardening (the hardness keeps increasing without softening) can be modeled by Avrami equation. [30,31] Unlike Equation (1), the fraction of transformation f is replaced by H e , which can be described as…”

Section: Age-hardening Behavior Of γ 0 /γ 00 Phasesmentioning

confidence: 99%

“…The early stages of hardening (the hardness keeps increasing without softening) can be modeled by Avrami equation. [ 30,31 ] Unlike Equation (), the fraction of transformation f is replaced by H e , which can be described as

H_{e} = \frac{H_{t} - H_{0}}{H_{\max} - H_{0}}

where H t is the hardness after aging time t , H 0 is the initial hardness, i.e., 275 HV, and H max is the peak hardness at different temperatures.…”

Section: As‐built and Solution‐treated Microstructuresmentioning

confidence: 99%

Isothermal Solid‐State Transformations of Inconel 718 Alloy Fabricated by Selective Laser Melting

Huang

Wang

2020

Adv Eng Mater

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Inconel 718 samples have been fabricated by selective laser melting (SLM) and subjected to a series of heat treatments to study the isothermal precipitation behaviors of δ, γ′, and γ″ phases. A time–temperature–transformation (TTT) diagram for as‐built Inconel 718 is finally plotted. The morphology, size, and distribution of δ phase are studied, and the corresponding transformation kinetics is analyzed by Avrami equation. The results demonstrate that the transformation rate at 900 °C is the highest, though the nose of the TTT curve occurs at 860 °C after an incubation period of 10 min. As the aging temperature increases (620–820 °C), the precipitation rate of γ′/γ″ increases and the time to reach peak hardness decreases. The nose of the TTT curve for γ′/γ″ precipitation occurs at 820 °C after only 32 s. Nevertheless, when aged above 720 °C, the peak hardness decreases. In addition, the age hardening can be described by Avrami equation when δ phase is absent (620–770 °C). In summary, SLMed Inconel 718 exhibits a faster precipitation kinetics compared with wrought material, whereas their phase transition temperatures are similar.

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Modeling age hardening kinetics of an Al–Mg–Si–Cu aluminum alloy

Cited by 34 publications

References 17 publications

Experimental investigations of stress-relaxation ageing behaviour of AA6082

Experimental investigations of stress-relaxation ageing behaviour of AA6082

Morphological Evolutions of Ni-Rich Phases in Al-Si Piston Alloys during 250–400 °C Thermal Exposure Processes

Isothermal Solid‐State Transformations of Inconel 718 Alloy Fabricated by Selective Laser Melting

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