Formation of a new intermediate phase and its evolution toward θ' during aging of pre-deformed Al-Cu alloys

Ma, Peipei; Liu, Chunhui; Ma, Zhi; Zhan, Lihua; Huang, Ming‐Hui

doi:10.1016/j.jmst.2018.11.022

Cited by 27 publications

(2 citation statements)

References 30 publications

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“…After ageing for 10 h, fine discoid/acicular T1 and θ' phase begin to precipitate unevenly, and there is little difference in the number ratio of the two precipitates. It can also be seen that both T1 and θ' phases precipitate along dislocation, which is consistent with the conclusion found in reference [21]. Moreover, the phase-orientation relationship of the two precipitates has been shown in the upper right corner of the graph, as shown in Figure 6(b-1,b-2).…”

Section: Evolution Of Microstructuresupporting

confidence: 90%

Study on Multi-Step Creep Aging Behavior of Al-Li-S4 Alloy

Xia

Zhan

et al. 2019

Metals

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Creep age forming (CAF) is a new technology developed for manufacturing large aluminum components in the aerospace industry. Aluminum–lithium alloys may be used in aerospace components because of their high modulus, specific strength and specific stiffness. Therefore, the creep deformation, mechanical properties and aging precipitation of Al-Li-S4 alloy under CAF conditions were studied. It was found that the creep behavior presents double steady state creep stages during the creep aging process. With the increase of stress level, the first steady creep rate increased, but the second steady creep rate was slightly reduced. Coincidentally, in the first steady state creep stage, the yield strength of the studied alloy also showed a slow increase stage. TEM observation showed that Al-Li-S4 alloy mainly contains two precipitation phases, T1 phase and θ’ phase. A few precipitates form during the first steady creep stage. Then, a lot of nucleation and growth of T1 phase resulted in rapid increase of yield strength. At the same time, the increase of stress level effectively inhibited the growth of T1 phase, which resulted in these strengthening phases being more uniform, and thus improved the mechanical properties of materials. On this basis, the relationship between the multi-step behaviors of creep, mechanical properties and aging precipitates are discussed. It is considered that the main reasons for the multi-step phenomenon of creep and mechanical properties are strongly related to the nucleation, growth and distribution of T1 phase.

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Section: Evolution Of Microstructuresupporting

confidence: 90%

Study on Multi-Step Creep Aging Behavior of Al-Li-S4 Alloy

Xia

Zhan

et al. 2019

Metals

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“…Second phases are usually apt to precipitate when possess lowest formation energy barrier, which depends on the combined effects of volume-free energy, strain energy and interfacial energy. The stress field around the dislocation introduced by the pre-deformation causes the crystal to have high energy, which is equivalent to increase the free energy of the phase transition, thus reducing the formation energy barrier of T 1 and θ′ [25][26][27]. Therefore, T 1 and θ′ are easy to precipitate quickly at dislocation after introducing pre-deformation.…”

Section: Phase Precipitation Behavior Analysismentioning

confidence: 99%

Effect of pre-deformation and artificial aging on fatigue life of 2198 Al-Li alloy

Zhang

Liang

et al. 2020

Mater. Res. Express

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The effects of pre-deformation and artificial aging on fatigue life of 2198 Al-Li alloy were explored to further reveal its fatigue behavior and improve the damage tolerance. Fatigue life was investigated on 2198-T3 alloy after pre-deformation and aging treatments. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to study the fracture morphology, precipitation behavior, fatigue crack initiation and propagation. Results indicated that T 1 (Al 2 CuLi) phase dominated the strengthening of 2198-T3 alloy after the further aging. Pre-deformation increased the number of dislocations in the matrix, which provided favorable position for nucleation of T 1 . The precipitation of θ′ (Al 2 Cu) and δ′ (Al 3 Li) were inhibited. Also, the formation and coarsening of precipitate-free zone (PFZ) were effectively avoided in this condition. Dislocation density in the 2198 Al-Li alloy matrix increased with the amount of pre-deformation, leading to an increase in microcrack defects on the surface and inside alloy. As a result, decreased fatigue life and an increased crack growth rate of the alloy were observed. Overall, 2198 Al-Li alloy had the best fatigue life and damage tolerance enhancement after it underwent 3% pre-deformation and was aged at 155°C for 15 h.

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Precipitates evolution and strengthening of Al–Mg2Si alloys containing high-Cu contents during ageing process

Sun

Zhou

et al. 2022

J Mater Sci

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Formation of a new intermediate phase and its evolution toward θ' during aging of pre-deformed Al-Cu alloys

Cited by 27 publications

References 30 publications

Study on Multi-Step Creep Aging Behavior of Al-Li-S4 Alloy

Study on Multi-Step Creep Aging Behavior of Al-Li-S4 Alloy

Effect of pre-deformation and artificial aging on fatigue life of 2198 Al-Li alloy

Precipitates evolution and strengthening of Al–Mg2Si alloys containing high-Cu contents during ageing process

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