The nucleation of recrystallization at second phase particles in 7000 series deformed aluminum alloy

Author(s):  
B. Hidalgo-Prada ◽  
J.J. Guilarte ◽  
S.Y. Paredes

An investigation was carried out to determine the effect of a thermomechanical process (TMP) in the precipitation of dispersed second phase particles, and to assess the recrystallization behavior of a deformed ALCANVEN-7475 commercial aluminum alloy. The TMP included solution anneal treatment at Ts = 482°C for 3 hours, overaging at temperatures (To) in the range from 160 - 400°c for 1 to 30 hours, cold and warm deformation up to 90% reduction of thickness (RA) and recrystallization at Tr = 482 °C for 15 to 60 minutes.A Hitachi H-600 TEM operated at 100 KV was utilized to examine the microstructural evolution of the alloy leading to the nucleation of recrystallization as a consecuence of the previously described four steps TMP.It was determined that the nucleation of recrystallized grains is promoted by the presence of second phase particles with critical sizes between 0.5 and 1.0 μm.

2014 ◽  
Vol 58 ◽  
pp. 535-542 ◽  
Author(s):  
P. Shaterani ◽  
A. Zarei-Hanzaki ◽  
S.M. Fatemi-Varzaneh ◽  
S.B. Hassas-Irani

2020 ◽  
Vol 24 ◽  
pp. 100956
Author(s):  
Fan Zhang ◽  
Yafei Wang ◽  
Yunbiao Duan ◽  
Kaijun Wang ◽  
Yutian Wang ◽  
...  

2020 ◽  
Vol 984 ◽  
pp. 31-42
Author(s):  
Bing Xue ◽  
Xue Mei Zong ◽  
Can Wang ◽  
Hua Yuan Zhang ◽  
Jing Luo

Basing on the study of adsorption behavior of glycidoxypropyl-trimethoxy-silane (GTMS), pretreatment method of AA2024-T3 aluminum alloy for sol-gel films was optimized. The morphology, composition and corrosion protective performance of alloy coated with the films were investigated by using FE-SEM, EDS, AFM and EIS. The results showed that the Al matrix exhibited better ability to adsorb GTMS molecules than the second phase particles, especially at lower concentration of GTMS. Further, the 5% GTMS films cover the whole surface, but the selective adsorption behaviors still exist. It was concluded that less second phase particles and smoother surface were benefit to the sol-gel films on aluminum alloy. Depending on this conclusion, the pretreatment method for sol-gel films was optimized. The optimized surface condition conducted with 50 g•L-1 sodium hydroxide and ultrasound at 60 oC for 30 s was obtained. These samples coated with the sol-gel films revealed good anti-corrosion performance. The coverage degree of the films was up to 97.95 %.


Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 777
Author(s):  
Yun Zhang ◽  
Haitao Jiang ◽  
Yujiao Wang ◽  
Zhe Xu

As an important fabrication process, annealing treatment is conducted to eliminate distortion in magnesium alloy sheets. Second-phase particles can provide nucleation sites for recrystallization grains, and the basal texture is related to the recrystallization behavior. Three experimental Mg-2Zn-based magnesium alloy sheets were investigated by the salt bath annealing process. Combined with variations in hardness softening, evolution of microstructure and basal texture, the effect of second-phase particles on microstructure evolution was analyzed. The results showed that the significant influence of size and distribution of second-phase particles on static recrystallization in magnesium alloy sheets was exhibited, which lead to the formation of two stages in the annealing process, combined with static recovery behavior. Second phase particles with coarse size were beneficial to recrystallization grains’ nucleation and increased recrystallization behavior in the initial stage of annealing. Second-phase particles with fine size inhibited recrystallization behavior and weakened the softening of hardness. The basal texture was weakened by second phase particles at the stage of recrystallization nucleation. The change in basal texture at the stage of grain growth was related to the size of second-phase particles. The regulation of basal texture enhancement can be envisioned by modifying second-phase particles.


2013 ◽  
Vol 753 ◽  
pp. 221-224 ◽  
Author(s):  
Krzysztof Sztwiertnia ◽  
Magdalena Bieda ◽  
Anna Korneva

In situ orientation mapping using TEM and calorimetric measurements were carried out to investigate the annealing behavior of cold-rolled 6013 aluminum alloy. The recrystallization of the material can be considered to be a number of processes that correspond to two separate stored energy release peaks. In the temperature range of the peak 1, the deformation zones around the large second-phase particles acted as sites for particle-stimulated nucleation. In the matrix, at the same time, some elongation of grains occurred. The elongated matrix grains appeared because of the reduction of the dislocation density and the annihilation of some low-angle grain boundaries between chains of subgrains lying in layers parallel to the sheet plane. The matrix processes in this temperatures range can be considered forms of continuous recrystallization. The matrix high-angle grain boundaries started to migrate at the temperature range of the peak 2. They moved mostly in the direction normal to the sheet plane. Heating of the sample for an appropriate time at those temperatures resulted in the complete discontinuous recrystallization of the material. The recrystallized microstructure was dominated now by elongated grains, which were a few times thicker than those obtained by annealing at the temperatures of the peak 1.


2011 ◽  
Vol 480-481 ◽  
pp. 433-436
Author(s):  
Mu Meng ◽  
Zhi Min Zhang ◽  
Jian Min Yu ◽  
Xin Kai Li

Aluminum alloy 7A04 compressed at high deformation temperature and large deformation is applied in two different heat treatment (T5 and T6), then microstructure and properties of the alloy after heat treatment are investigated. The mechanical properties are studied by means of the tensile testing and the hardness testing. The microstructure characteristics and the fractorgraphy analysis are respectively investigated with optical microscopy and SEM. The experimental results indicate that after T6 heat treatment, the second-phase particles dispersed in the matrix, which can efficiently improving the strength of the alloy, but reduced the toughness. After T5 heat treatment, the coarse and discontinuous second-phase is distributed along the grain boundary, which can lead to the low strength and high toughness because of the lack of the strengthening phase in the grains. The fracture appearance is intercrystalline fracture after T6 heat treatment, and dimple transgranular fracture after T5 heat treatment.


2010 ◽  
Vol 163 ◽  
pp. 13-18 ◽  
Author(s):  
M. Bieda-Niemiec ◽  
Krzystof Sztwiertnia ◽  
A. Korneva ◽  
Tomasz Czeppe ◽  
R. Orlicki

Orientation mapping in transmission electron microscope was successfully applied to study microstructural changes at the initial stage of recrystallization in the aluminum alloy with a bimodal second-phase particle distribution. The alloy samples were reversibly cold rolled resulting in the formation of laminar structure with zones of localized strain around large second-phase particles. Orientation mapping and in-situ investigations carry information about the processes which are active in the deformation zones during annealing.


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