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Strain dependence of deformation and recrystallization microstructure homogeneity in clock-rolled tantalum sheets

Zhu, Jialin ; Liu, Shifeng ; Yang, Shuai ; Long, Doudou ; Liu, Yahui ; Yuan, Xiaoli and Orlov, Dmytro LU (2020) In Materials Characterization 161.
Abstract

Microstructure and crystallographic texture are the key factors that determine the sputtering target properties. Clock rolling plays an important role in improving the microstructure homogeneity, but the effect of strain during rolling on deformation and recrystallization behavior is not clear. Thus, high-purity tantalum (Ta) plates were 135° clock rolled to 70% and 87% reduction and then annealed at various temperatures to observe the microstructure evolution. Texture and microstructure in the center layer of the rolled and annealed Ta sheets were characterized via optical microscope (OM), X-ray diffraction (XRD), electron backscatter diffracting (EBSD) and transmission electron microscope (TEM). The results displayed that significant... (More)

Microstructure and crystallographic texture are the key factors that determine the sputtering target properties. Clock rolling plays an important role in improving the microstructure homogeneity, but the effect of strain during rolling on deformation and recrystallization behavior is not clear. Thus, high-purity tantalum (Ta) plates were 135° clock rolled to 70% and 87% reduction and then annealed at various temperatures to observe the microstructure evolution. Texture and microstructure in the center layer of the rolled and annealed Ta sheets were characterized via optical microscope (OM), X-ray diffraction (XRD), electron backscatter diffracting (EBSD) and transmission electron microscope (TEM). The results displayed that significant microstructure difference existed between 70% and 87% sample. Grain average misorientation value of {111} grains {〈111〉//normal direction (ND)} in the 70% sample was considerably higher than that in the 87% sample, suggesting a more heterogeneous grain fragmentation. Schmid factor (SFrolling) and Taylor model analysis of {111} grains in the 70% sample demonstrated that the slip was easier, and the system with higher SFrolling could alone accommodate the majority of plastic strain, contributing to the formation of micoshear bands. Upon annealing, the sample rolled 70% recrystallized more quickly, owing to strong {111} deformed texture, and severe microstructure subdivision and great stored energy within {111} grains. The {111} texture is very strong and grain size distribution was not uniform after the completion of recrystallization. However, after annealing of sample rolled 87%, smaller average grain size and variation, and relatively homogeneous texture distribution can be obtained.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Microstructure, Schmid factor, Strain, Taylor model, Texture
in
Materials Characterization
volume
161
article number
110165
publisher
Elsevier
external identifiers
  • scopus:85078409934
ISSN
1044-5803
DOI
10.1016/j.matchar.2020.110165
language
English
LU publication?
yes
id
a19c4780-be32-420c-a620-6965ab8faab9
date added to LUP
2020-02-04 13:31:11
date last changed
2020-02-12 10:20:35
@article{a19c4780-be32-420c-a620-6965ab8faab9,
  abstract     = {<p>Microstructure and crystallographic texture are the key factors that determine the sputtering target properties. Clock rolling plays an important role in improving the microstructure homogeneity, but the effect of strain during rolling on deformation and recrystallization behavior is not clear. Thus, high-purity tantalum (Ta) plates were 135° clock rolled to 70% and 87% reduction and then annealed at various temperatures to observe the microstructure evolution. Texture and microstructure in the center layer of the rolled and annealed Ta sheets were characterized via optical microscope (OM), X-ray diffraction (XRD), electron backscatter diffracting (EBSD) and transmission electron microscope (TEM). The results displayed that significant microstructure difference existed between 70% and 87% sample. Grain average misorientation value of {111} grains {〈111〉//normal direction (ND)} in the 70% sample was considerably higher than that in the 87% sample, suggesting a more heterogeneous grain fragmentation. Schmid factor (SF<sub>rolling</sub>) and Taylor model analysis of {111} grains in the 70% sample demonstrated that the slip was easier, and the system with higher SF<sub>rolling</sub> could alone accommodate the majority of plastic strain, contributing to the formation of micoshear bands. Upon annealing, the sample rolled 70% recrystallized more quickly, owing to strong {111} deformed texture, and severe microstructure subdivision and great stored energy within {111} grains. The {111} texture is very strong and grain size distribution was not uniform after the completion of recrystallization. However, after annealing of sample rolled 87%, smaller average grain size and variation, and relatively homogeneous texture distribution can be obtained.</p>},
  author       = {Zhu, Jialin and Liu, Shifeng and Yang, Shuai and Long, Doudou and Liu, Yahui and Yuan, Xiaoli and Orlov, Dmytro},
  issn         = {1044-5803},
  language     = {eng},
  publisher    = {Elsevier},
  series       = {Materials Characterization},
  title        = {Strain dependence of deformation and recrystallization microstructure homogeneity in clock-rolled tantalum sheets},
  url          = {http://dx.doi.org/10.1016/j.matchar.2020.110165},
  doi          = {10.1016/j.matchar.2020.110165},
  volume       = {161},
  year         = {2020},
}