An investigation of strain fields in dispersion strengthened aluminium by convergent beam electron diffraction

Wittmann, R.; Kruse, Paul W.; Frauenkron, M.; Gerthsen, D.

doi:10.1080/01418610008216470

Cited by 7 publications

(5 citation statements)

References 18 publications

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“…However, it was found for all three zone axes studied, that by adjusting the a , c and γ values at a set ratio, a series of equivalent solutions resulted instead of a unique solution being produced. Others have similarly seen that after a fitting algorithm determined a satisfactory solution, further iterations produced different, equally good solutions (Wittmann et al , 2000). Therefore, in this research, the relaxation in the [110] direction was calculated to be 0.10% using the method shown previously (Diercks et al , 2009).…”

Section: Defining Variablesmentioning

confidence: 99%

Using a <670> zone axis for convergent beam electron diffraction measurements of lattice strain in strained silicon

Diercks

Kaufman

Irwin

et al. 2010

Journal of Microscopy

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SummaryConvergent beam electron diffraction patterns of silicon from the gate channel region of a complementary metal-oxidesemiconductor transistor with recessed Si .82 Ge .18 stressors were analysed using three zone axes: <230>, <340> and <670>. Values measured using these axes were compared with each other with regards to strain along the [110] and the [001] directions. It was demonstrated that strain measurements made using all three axes showed reasonable agreement with each other: an increase in the [110] compressive strain and a switch from compressive to tensile strain in the [001] with decreasing distance below the gate. It was also observed that the strain calculations using the <230> axis had the lowest uncertainty whereas the <670> axis allowed for measurements closest to the gate due to the improved lateral resolution at that tilt angle.

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Section: Defining Variablesmentioning

confidence: 99%

Using a <670> zone axis for convergent beam electron diffraction measurements of lattice strain in strained silicon

Diercks

Kaufman

Irwin

et al. 2010

Journal of Microscopy

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“…three independent variables) is helpful to solve the problem concerning the relaxation in thin TEM foils, but the multisolution problem appears (Maier et al 1996, Wittmann et al 2000. If the model of tetragonal distortion is applied, the error of the determination of the lattice parameters may increase because of the neglect of possible relaxation.…”

Section: Evaluation Of Lattice Parametersmentioning

confidence: 99%

Measurement of local elastic strains in the single-crystal nickel-based superalloy CMSX-6 by convergent-beam electron diffraction

Pyczak

Biermann

et al. 2002

Philosophical Magazine A

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High spatial resolution convergent beam electron diffraction (CBED) was used in this study as a powerful tool to investigate the local lattice parameters (and elastic strains) in the y and y' phases of the single-crystal nickel-based superalloy CMSX-6 a t room temperature, before and after high-temperature creep deformation in tension. With the aid of a newly implemented improved fast evaluation procedure, it was possible to determine the elastic strains in a large number of positions in the microstructure. The experimental results are in global agreement with earlier work but more specific with regard to details. Thus, it is confirmed that compressive elastic stresses exist in both horizontal and vertical y channels in the initial state and that, after tensile creep at 98OoC, in agreement with an earlier dislocation model, the elastic strains in the horizontal y channels change from the compressive to a tensile state, acting perpendicular to the deformation axis, while the strain state in the vertical channels is only modified quantitatively. As a new result, it is noted that while the elastic strain in y' particles is initially homogeneous, an inhomogeneous distribution of the elastic strains in the y' phase is observed after high-temperature creep. The findings reported demonstrate the capability of the improved time-saving CBED evaluation procedure with respect to the reliable determination of local lattice parameters in fine-scale microstructures.

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“…However, these approaches do not ascertain unique strain components (cf. [4,5]). In these circumstances, the ambiguity problem is addressed by assumptions about the nature of strain, i.e.…”

Section: Introductionmentioning

confidence: 97%

“…Questions about the dimensionality of the manifold of indeterminable parameters were asked by Wittmann et al [5]. Among various approaches to resolve the issue, these of Toda et al [6] and Kra¨mer et al [7] are closest to our way of thinking.…”

Section: Introductionmentioning

confidence: 98%

Formal conditions for unambiguous residual strain determination by CBED

Morawiec¹

2005

Philosophical Magazine

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The method of residual strain determination using convergent beam electron diffraction (CBED) is attractive because of its good spatial resolution. However, attempts to obtain all six independent strain components from a CBED pattern lead to ambiguous results. This paper contains analysis of the ambiguities based on the complete algorithm for matching experimental and strain-dependent simulated CBED patterns. The strain parameters which are not determinable by the CBED method are identified by examination of the most common goodness-of-fit functions. The indeterminable parameters are confirmed to be the '13' and '23' components and a combination of the diagonal components of the tensor given in the Cartesian systems having the '3' axis parallel to the beam direction. The ambiguity can be eliminated based on multiple diffraction patterns. It is shown that two different patterns may be insufficient to get a unique strain tensor. The ambiguity can be removed only if certain characteristics of the two patterns are different, or if more than two patterns are used.

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An investigation of strain fields in dispersion strengthened aluminium by convergent beam electron diffraction

Cited by 7 publications

References 18 publications

Using a <670> zone axis for convergent beam electron diffraction measurements of lattice strain in strained silicon

Using a <670> zone axis for convergent beam electron diffraction measurements of lattice strain in strained silicon

Measurement of local elastic strains in the single-crystal nickel-based superalloy CMSX-6 by convergent-beam electron diffraction

Formal conditions for unambiguous residual strain determination by CBED

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