Some applications of HRTEM for the study of defects

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Some applications of HRTEM for the study of
defects
Bariloche city
PASI on Transmission Electron Microscopy Santiago
de Chile, July 2006
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CuZnAl Shape Memory Alloy Hysteresis cycle in the
?? - 2H transformation
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Twinned 2H martensite
Lattice invariant shear by twinning
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Changes of the dislocation Burgers vectors
? phase (BCC)
2H martensite
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Dislocations and stacking faults in the 2H
martensite
Philips CM200 200 kV LaB6
Cs 0.5 nm Point
resol. 0.19 nm
Interaction with the twin boundary
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Twin interface observed along the 210 direction
Twin Plane 121
A.M. Condó, F. Lovey, V. Torra, Phil. Mag., 83
(2003) 1479.
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Twin boundary symmetry in 2H martensite
Mirror antisymmetry
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Simulated images along 210 of 2H martensite
2H Structure
Simulated
Experimental
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Models for the twin interface structure
?  0.0262 nm.
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Simulated images of the twin boundary
Model c
Models a, b and c
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Average intensity of the planes parallel to the
twin interface
Best matching for the model c
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Distances between the planes parallel to the
interface
Best matching for the model c
The atomic volume is preserved at the twin
boundary
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Calculated structure for the (1011) twin interface
Serra A., Bacon D.J., Phil. Mag. A, 63 (1991) 1001
Pond R.C., Bacon D.J., Serra A., Phil. Mag. A, 71
(1995) 275
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Interaction of the twin interface with a stacking
fault
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Interaction between stacking fault and twin
interface
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Coalescence of one twin variant under applied
stress
Defects parallel to the twin boundary are created
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Basal and 121faults
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Column displacements around the 121fault
?c1 (0.06?0.02) c
?c2 (0.09?0.02) c
?c3 (0.05?0.02) c
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Fault structure and relaxations
Hard sphere model ?c 0.10 c
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Supercel
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Fault simulated images
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Comparison of the displacements
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Conclusions
The 121 twin boundary in the 2H martensite has
a mirror antisymmetry and the atomic volume is
preserved
The stacking faults, created due to the
interaction with the existing dislocations, are
absorbed by the twin boundary by creating
interface dislocations
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Defects produced by swift and heavy ions in a
monoclinic structure of Cu-based alloy
Xe at 230 Mev
Fluency 1014
Different defocus
From PhD Thesis of Eugenia Zelaya, Instituo
Balseiro, 2006
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Defects produced by fast and heavy ions
From PhD Theses of Eugenia Zelaya, Instituo
Balseiro, 2006
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Models for the super cell
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Simulations
22 nm
50 nm
22 nm
50 nm
Df
T
3,1 nm
6,2 nm
9,3 nm
12,4 nm
Inclined illumination 0.2 deg
From PhD Theses of Eugenia Zelaya, Instituo
Balseiro, 2006
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1?1 1
2 0 0
1 1?1
20 nm
Bright field image of commercial 7012 (Al-Zn-Mg)
8 min 160ºC. Spherical GP zones and hexagonal ?
precipitates with habit planes parallel to 111
matrix planes.
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Commercial 7012 (Al-Zn-Mg) alloy 8 min 160C
1 1?1
2 0 0
1?1 1
? precipitates Hexagonal c 1.403 nm a
0.496 nm
Guinier-Preston Zones (2 3 nm)
Al
2 nm
A. Tolley Centro Atómico Bariloche
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N. Haberkorn, F. Lovey, A.M. Condó, J. Guimpel,
J. Appl. Physics, 97 (2005) 53511
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Interface structure
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Interface with stacking Ba2O/MnO2. The simulated
image correspond to one defocus and thickness
value of -49 and 3 nm, respectively.
Interface with stacking CuO/MnO2, a shift of the
f100g planes is observed at the interface.
Simulated image correspond to defocus and
thickness value of -49 and 3 nm, respectively,
with an inclinated illumination of 0.27.
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Staking faults in manganite and superconductor
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(No Transcript)
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A.M. Condó, J. Guimpel., F. Lovey, Centro Atómico
Bariloche, 2006
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Películas delgadas de Cu-Al-Ni
Microestructura de la película depositada
Espesor 4 mm
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Thin films of Cu-Al-Ni
Phases and crystalline texture
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Diffraction
e-
R-x
- d 0.211 nm - textura
Hexagonal a 0.462 nm b 0.534 nm c 0.422
nm (c/a)hex 1.58 Y 1
BCC a 0.298 nm (bulk 0.292 nm)
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Thanks very much for your patience