Atomic scale observation of the displacement fields generated by the intrinsic defects of {111}Ni<sub>3</sub>AI/(0 1 0)Ni<sub>3</sub>Nb close-packed interfaces

Bonnet, R.; Loubradou, M.; Dahmen, U.

doi:10.1080/01418610008216471

Cited by 15 publications

References 31 publications

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Atomic Resolution Scanning Transmission Electron Microscopy

Browning

Arslan

Moeck

et al. 2001

phys. stat. sol. (b)

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Recent developments in scanning transmission electron microscopy (STEM) now make it routinely possible to obtain direct images and spectra from interface and defects structures with atomic spatial resolution. Here we describe the experimental conditions required to set‐up and align a 200 kV STEM/TEM microscope to perform this analysis. The various imaging and analysis techniques will be illustrated with examples from interfaces in II–VI and III–V quantum dot systems and dislocation cores in GaN.

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Atomic Resolution Scanning Transmission Electron Microscopy

Browning

Arslan

Moeck

et al. 2001

phys. stat. sol. (b)

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HRTEM Observation of a ?113?? Low Angle Tilt Boundary in the Al-Al2Cu(?) Eutectic Composite

Belgacem

Fnaiech

Loubradou

et al. 2002

phys. stat. sol. (a)

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Particular defect structures appear during directional solidification of the Al(fcc)-Al 2 Cu(q) lamellar eutectic composite, the so-called lamellar faults. Each fault corresponds to terminations of Al and q lamellae. These terminations consist of a continuous succession of three types of ribbon-like interfaces, among which two are low angle boundaries: one is located in the fcc phase and the other in the q intermetallic (C16 standard type, a = 0.6063 nm, c = 0.4872 nm). High resolution transmission electron microscopy (HRTEM) of a q/q low angle tilt boundary with an electron beam parallel to h113iq shows that the core structures of the dislocations are undissociated despite the large magnitude of the possible Burgers vectors. The dislocations are of mixed-type character and oriented along the h113iq direction the closest to the growth axis direction of the eutectic. An unusual defect present in the tilt boundary consists of a dense group of three dislocations separated by nanometric distances. This defect acts like a single dislocation at far field distance. The mechanical equilibrium of such a defect has been studied using isotropic and anisotropic elasticities. It is strongly suggested that two of these dislocations form a dipole, which would indicate that the boundary has not a completely relaxed structure.

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Crystalline Defects in a B.C.T. Al2Cu(?) Single Crystal Obtained by Unidirectional Solidification along [001]

Bonnet

Loubradou

2002

phys. stat. sol. (a)

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A directionally solidified Al2Cu(θ) crystal (body centred tetragonal lattice, a = 0.6063 nm, c = 0.4872 nm) grown along the c axis has been observed by transmission electron microscopy (TEM) to investigate the solidification defects. In a first step, using two‐beam TEM, matrix dislocations with large Burgers vectors 1/2〈111〉, [001], and [100] were positively identified, as well as a rectangular spiral source with a Burgers vector b = 1/2[$ \bar 1 \bar 1 \bar 1 $] acting along the ($ \bar 1 \bar 1 $2) plane. These defects were identified from the comparison between sets of experimental and theoretical images. It is shown that the topological contrasts of these dislocations can be highly affected by the elastic relaxation at both free surfaces of the thin foil. In a second step, a (110) facetted low angle tilt boundary with the c axis has been investigated by high resolution TEM. Its structure can be described as a succession of two consecutive mixed dislocations b = 1/2[111] and 1/2[11$ \bar 1 $], which gives for the pair an edge resultant Burgers vector [110]. A quite unusual core splitting is observed for one of these mixed dislocations since narrow faults extend on the (110) boundary plane. Around this complex core, the relative positions of the partials have been carefully determined at a near atomic scale using a dedicated simulation program using anisotropic elasticity theory. Large planar faults along (001) are also sometimes noticed. These results stress that, in the characterisation of crystalline defects in crystals with large lattice parameters, numerical methods provide an important advantage over classical methods based on qualitative arguments only.

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Atomic scale observation of the displacement fields generated by the intrinsic defects of {111}Ni₃AI/(0 1 0)Ni₃Nb close-packed interfaces

Cited by 15 publications

References 31 publications

Atomic Resolution Scanning Transmission Electron Microscopy

Atomic Resolution Scanning Transmission Electron Microscopy

HRTEM Observation of a ?113?? Low Angle Tilt Boundary in the Al-Al2Cu(?) Eutectic Composite

Crystalline Defects in a B.C.T. Al2Cu(?) Single Crystal Obtained by Unidirectional Solidification along [001]

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Atomic scale observation of the displacement fields generated by the intrinsic defects of {111}Ni3AI/(0 1 0)Ni3Nb close-packed interfaces

Cited by 15 publications

References 31 publications

Atomic Resolution Scanning Transmission Electron Microscopy

Atomic Resolution Scanning Transmission Electron Microscopy

HRTEM Observation of a ?113?? Low Angle Tilt Boundary in the Al-Al2Cu(?) Eutectic Composite

Crystalline Defects in a B.C.T. Al2Cu(?) Single Crystal Obtained by Unidirectional Solidification along [001]

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Atomic scale observation of the displacement fields generated by the intrinsic defects of {111}Ni₃AI/(0 1 0)Ni₃Nb close-packed interfaces