Effects of initial microstructure on hot deformation behavior of Al-7.9Zn-2.7Mg-2.0Cu (wt%) alloy

Zang, Qianhao; Yu, Huashun; Lee, Yun‐Soo; Kim, Minseok; Kim, Su-Hyeon

doi:10.1016/j.matchar.2019.03.019

Cited by 67 publications

(16 citation statements)

References 44 publications

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“…For example, it can be seen from Figure 8 that a large number of near micrometer-sized second-phase particles are precipitated during the air cooling after homogenization, which potentially may act as nucleation sites for recrystallization through the accumulated stored energy in their immediate vicinity, and hence being potent nucleation sites for recrystallization (i.e., particle-stimulated nucleation (PSN) of recrystallization). [21][22][23][24] However, the effect of these second-phase particles for possible differences in the recrystallization behavior can be ignored in this study because there is no obvious difference between these two alloys with respect to the size and number density of these second-phase particles. Moreover, the particles size of almost all of the second-phase particles in Figure 8 is less than 1 lm.…”

Section: Discussionmentioning

confidence: 99%

Microstructure Evolution and Recrystallization Resistance of a 7055 Alloy Fabricated by Spray Forming Technology and by Conventional Ingot Metallurgy

Xie

Jia

Xiang

et al. 2020

Metall Mater Trans A

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The effect of different fabricating processes (spray forming and conventional casting) and homogenization treatment on the microstructure of an 7055 alloy was investigated by optical microscopy (OM), scanning electron microscopy (SEM), electron probe X-ray micro-analyzer (EPMA), and transmission electron microscopy (TEM). It was found that the grain size of the as-deposited (spray formed) 7055 alloy had half the size as that of the as-cast 7055 alloy and there was no Al 2 CuMg phase that embedded in the coarse Mg(Zn, Cu, Al) 2 phase distributed along the grain boundaries in the as-deposited 7055 alloy. No segregation of zirconium was observed in the as-deposited 7055 alloy. After homogenization heating at 350°C/5 hours + 470°C /24 hours, Al 3 Zr dispersoids were inhomogeneously distributed within grains in the traditionally cast 7055 alloy, while more homogeneously distributed within grains in the spray-formed 7055 alloy. Compared with the traditional cast 7055 alloy, the uniform distribution of Al 3 Zr dispersoids in the spray-formed 7055 alloy retards recrystallization more effectively. This investigation highlights the advantage of spray forming technology on improving microstructure of a 7055 alloy.

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Section: Discussionmentioning

confidence: 99%

Microstructure Evolution and Recrystallization Resistance of a 7055 Alloy Fabricated by Spray Forming Technology and by Conventional Ingot Metallurgy

Xie

Jia

Xiang

et al. 2020

Metall Mater Trans A

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“…At the lnZ value of 25.8, the local misorientation and cumulative misorientations along the black vector of Figure 9 b are shown in Figure 10 b. The cumulative misorientations along the vector increase continuously and exceed 12°, which suggests that progressive subgrain rotation has been developed from the grain center to grain boundary [ 39 , 40 ]. When lnZ value reaches 21.7, the adjacent grains and subgrains are separated by low-misorientation grain boundaries, as shown by the black circle in Figure 9 c. This phenomenon is suggested to result from the division of original grains, as recrystallization occurring with the dislocation density and grain misorientation rising.…”

Section: Discussionmentioning

confidence: 99%

Hot Deformation Behavior and Workability of In-Situ TiB2/7050Al Composites Fabricated by Powder Metallurgy

Zhu

Liu

et al. 2020

Materials

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Isothermal compression tests of in situ TiB2/7050Al composites fabricated by powder metallurgy were performed at 300–460 °C with the strain rate varying from 0.001 s−1 to 1 s−1. The Arrhenius constitutive equation and hot processing map of composites were established, presenting excellent hot workability with low activation energies and broad processing windows. Dramatic discontinuous/continuous dynamic recrystallization (DDRX/CDRX) and grain boundary sliding (GBS) take place in composites during deformation, depending on the Zener-Hollomon parameter (Z) values. It was found that initially uniform TiB2 particles and fine grain structures are beneficial to the DDRX, which is the major softening mechanism in composites at high Z values. With the Z value decreasing, dynamic recovery and CDRX around particles are enhanced, preventing the occurrence of DDRX. In addition, fine grain structures in composites are stable at elevated temperature thanks to the pinning of dense nanoparticles, which triggers the occurrence of GBS and ensures good workability at low Z values.

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“…Zang et al discussed the effect of initial microstructure on the hot deformation behavior of Al-Zn-Mg-Cu alloy. However, strain compensation was not considered in developing the constitutive model [23]. Despite the progress achieved in the abovementioned studies in exploring the flow behavior and recrystallization mechanism of Al-Zn-Mg-Cu alloys, few studies have focused on the hot deformation behavior considering strain effects and discussed the relationship between the second phase and the microstructural evolution in detail.…”

Section: Introductionmentioning

confidence: 99%

Hot Deformation Behavior Considering Strain Effects and Recrystallization Mechanism of an Al-Zn-Mg-Cu Alloy

et al. 2020

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The hot deformation behavior of an Al-Zn-Mg-Cu alloy was investigated by hot compression test at deformation temperatures varying from 320 to 440 °C with strain rates ranging from 0.01 to 10 s−1. The results show that the Mg(Zn, Cu)2 particles as a result of the sufficient static precipitation prior to hot compression have an influence on flow softening. A constitutive model compensated with strain was developed from the experimental results, and it proved to be accurate for predicting the hot deformation behavior. Processing maps at various strains were established. The microstructural evolution demonstrates that the dominant dynamic softening mechanism stems from dynamic recovery (DRV) and partial dynamic recrystallization (DRX). The recrystallization mechanism is continuous dynamic recrystallization (CDRX). The microstructure observations are in good agreement with the results of processing maps. On account of the processing map and microstructural observation, the optimal hot processing parameters at a strain of 0.6 are at deformation temperature range of 390–440 °C and strain rate range of 0.010–0.316 s−1 with a peak efficiency of 0.390.

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Effects of initial microstructure on hot deformation behavior of Al-7.9Zn-2.7Mg-2.0Cu (wt%) alloy

Cited by 67 publications

References 44 publications

Microstructure Evolution and Recrystallization Resistance of a 7055 Alloy Fabricated by Spray Forming Technology and by Conventional Ingot Metallurgy

Microstructure Evolution and Recrystallization Resistance of a 7055 Alloy Fabricated by Spray Forming Technology and by Conventional Ingot Metallurgy

Hot Deformation Behavior and Workability of In-Situ TiB2/7050Al Composites Fabricated by Powder Metallurgy

Hot Deformation Behavior Considering Strain Effects and Recrystallization Mechanism of an Al-Zn-Mg-Cu Alloy

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