Deformation study of copper using in

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Deformation study of copper using
in-situ EBSD and FSD imaging
Pawel NOWAKOWSKI(1) , Raphaël PESCI(2) , Marc WARY(2) 1)Oxford Instruments France
2)ENSAM Metz France
BORDEAUX 2014
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Why in‐situ analyses? Observation of local evolution of microstructure during:
‐ tempering / annealing ‐ mechanical loading (tension, compression, bending…) Better comprehension of physical mecanisms such as:
‐ recrystallization
‐ deformation ‐ phase transformation
‐…
These kinetic critical phenomena require: ‐ in‐situ devices for heating / cooling and / or loading ‐ analytical detectors allowing fast acquisitions
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Evolution of indexing rates with HKL systems
Recent increase of the development and the miniaturization of devices for SEM: loading, heating and cooling
870Hz
*Micomachine MicroMecha SAS 99% d’indexation sur Ni
EBSD coupled with in‐situ analyses allow to study the evolution of micro‐textures and the variations near grain boundaries © Oxford Instruments 2013
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Material
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Copper starting sheet
RD
TD
{111} and {100} texture Z (ND)
RD
X (TD)
50 µm
Electrolytical polishing
Nordlys S , 20kV Step: 0.25µm
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Y (RD)
IPF // Y (RD)
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Material
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1mm thick Cu sheet was heated at 930°C for 1h in order to increase the grains size Z (ND)
X (TD)
RD
50 µm
Y (RD)
IPF // Y (RD)
Grains size chanched
10µm 150µm
{111} texture is
conserved
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Three points bending test
Supporting pins
specimen
Loading pins
Force
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Three points bending test
T ‐ Tension
Neutr
al axis
Force
C ‐ Compression
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Three points bending in-situ test + EBSD analyses
Nordlys S
HT: 20kV Acc. speed: 40 Hz Step size: 2 µm
Displacement / loading force curve and EBSD analyze points
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FSD image contrast and EBSD IPF map after three points in‐situ bending test
Neutral region
Neutral region
Compression
region
Tension region
IPF // Z © Oxford Instruments 2013
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Tension region
Compression
region
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0 mm
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200 µm
IPF // Z X0
Y0
Z0
001
111
101
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0.1 mm
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200 µm
IPF // Z X0
Y0
Z0
001
111
101
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0.27 mm
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200 µm
IPF // Z X0
Y0
Z0
001
111
101
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0.5 mm
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200 µm
IPF // Z X0
Y0
Z0
001
111
101
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1.0 mm
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200 µm
X0
Y0
Z0
001
111
101
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2.0 mm
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200 µm
IPF // Z X0
Y0
Z0
001
111
101
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3.4 mm
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200 µm
IPF // Z X0
Y0
Z0
001
111
101
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3.4 mm
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X0
Y0
Z0
001
111
101
Compression
Compression
Compression
region
region
region
al
u tr
Ne
is
ax
Tension region
Tension region
IPF // Z 200 µm
200 µm
200 µm
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How the deformation processes??
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{100}
Y0
X0
Cal for all grains in the map
{110}
IPF // Z {111}
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{100}
Y0
X0
Cal for all grains in the map
{110}
IPF // Z {111}
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{100}
Y0
X0
Cal for all grains in the map
{110}
IPF // Z {111}
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{100}
Y0
X0
Cal for all grains in the map
{110}
IPF // Z {111}
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{100}
Y0
X0
{110}
IPF // Z {111}
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{100}
Y0
X0
Cal for all grains in the map
{110}
IPF // Z {111}
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{100}
Y0
X0
{110}
IPF // Z {111}
No significant rotation is observed
200 µm
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Primary slip system
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Slip plane
normal
Applied stress  axis
According to Schimd’s Low, the tensile
stress  at which the material start to slip
could be write as :


Slip direction
Schmid factor (SF)
Slip plane
The high Schmid factor value indicates the slip system which should be first activated ‐ this is know as primary slip system.
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Primary slip system
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Schmid factor distribution for starting sheet (at 0 strain): the high‐(in red) and low‐(blue)
0 strain
The high Schmid factor value indicates the slip system which should be first activated ‐ this is know as primary slip system.
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No slip markings are observed Slip system should to be activated when slip markings are observed at the surface.
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T1
Slip markings are observed only on one grin in tensile region T1
Slip system should to be activated when slip markings are observed at the surface.
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T1
T3
Others grains in tensile region are activated T2
T1
T2
T2
Slip system should to be activated when slip markings are observed at the surface.
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T1
T4
T5
More grains in tensile region are activated T3
T7
T6
T2
T1
T4
T5
T3
T7
T6
T2
Slip system should to be activated when slip markings are observed at the surface.
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T1
T4
T5
T3
T7
C7
C10C2
C6
C3
The grains in compression region are activated C9
C4
T6
C1
C5
T2
T1
T4
T3
T7
T6
T2
C7
T5
C10C2
C3
C6
C9
C4
C1
C5
Slip system should to be activated when slip markings are observed at the surface.
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T1
T4
C7
C10C2
C3
T5
T3
T7
C6
C9
Deformation progresses by
multiplying the slip systems C4
T6
C1
C5
T2
C8
T1
T4
T5
T3
T7
T6
C7
C10C2
C3
C6
C9
C4
C1
C5
T2
C8
Slip system should to be activated when slip markings are observed at the surface.
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T4
T1
T5
N1
Deformation progresses by
multiplying the slip systems N2
N6
T3
T7
N4
T6
N5
T2
T5
T4
T3
T1
No slip markers in neutral axis region have been observed T7
N1
N2
N6
N3
N4
T6
200 µm
T2
N5
Slip system should to be activated when slip markings are observed at the surface.
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T1
T4
T8
T6
T3
T9
T7
T1
T4
T8
T6
T2
C6
C9
C4
C1
T10
T2
Activated slip systems
C7
C10C2
C3
T5
C5
T11
T5
T3
T9
T7
C8
C7
C10C2
C3
C9
C6
C4
SFT
Slip system
T1
0.46
(1‐11) <110>
T2
0.41
(‐111) <‐1‐10>
T3
0.46
(‐1‐11) <‐110>
T4
0.35
(‐111) <‐1‐10>
T5
0.5
(‐111) <101>
T6
0.41
(1‐11) <0‐1‐1>
T7
0.48
(‐111) <‐1‐10>
T8
0.45
(‐1‐11) <‐110>
T9
0.48
(111) <‐101>
T10
0.4
(‐111) <101>
T11
0.49
(‐111) <‐1‐10>
Slip plane (‐111)
C1
T10
T11
Grain
C5
C8
Only one slip system has been activated in each grain during the bending test
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Activated slip systems
C7
C10C2
C3
C6
C9
C4
C1
C5
C8
C7
C10C2
C3
C9
C6
C4
Grain
SFT
Slip system
C1
0.45
(‐111) <‐1‐10>
C2
0.45
(1‐11) <0‐1‐1>
C3
0.45
(1‐11) <0‐1‐1>
C4
0.44
(1‐11) <0‐1‐1>
C5
0.46
(1‐11) <110>
C6
0.46
(‐111) <101>
C7
0.44
(‐111) <01‐1>
C8
0.49
(1‐11) <110>
C9
0.46
(‐1‐11) <‐110>
C10
0.46
(111) <01‐1>
Slip plane (1‐11)
C1
C5
C8
Only one slip system has been activated in each grain during the bending test
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Activated slip systems
N1
N2
N3
N5
N5
N6
N1
Grain
SFT
Slip system
N1
0.34
(‐111) <‐1‐10>
N2
0.34
(‐111) <‐1‐10>
N3
0.35
(‐111) <‐1‐10>
N4
0.36
(‐111) <‐1‐10>
N5
0.36
(‐111) <101>
N6
0.33
(‐111) <01‐1>
No slip plane active
N2
N3
N4
N6
N5
Only one slip system has been activated in each grain during the bending test
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Conclusions
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1) EBSD measurements combined with FSD imaging is very efficient in deformation study under tensile / compressive conditions
2) Some texture components are reinforced during bending
3) No significant grains rotation is observed during deformation
4) Only one slip system has been activated for each grain in tensile and compression region. No slip system has been activated in neutral axis region
5) ‐ Most likely the (‐111) slip plane has been activated in tension region 6) ‐ Most likely the (1‐11) in compression region
7) The first activated slip system is not that one with the highest Schmid factor. This
suggests that the slip activity within a grain is not only influenced by its crystallographic orientation, but also by the orientation and slip activity of its neighbors
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Next steps
1) Study of slip transmission from one grain to neighboring grains
2) Useof DIC analyses for FSD images analyses
3) Confirm the deformation mechanism in case of small copper grains
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Thanks
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