Electron diffraction based techniques in scanning electron microscopy of bulk materials

Wilkinson, Angus J.; Hirsch, P. B.

doi:10.1016/s0968-4328(97)00032-2

Cited by 298 publications

(209 citation statements)

References 85 publications

(137 reference statements)

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“…The ECCI is a scanning electron microscopy (SEM) imaging technique with sufficient sensitivity to clearly visualize the local crystallographic orientation and the dislocations near the specimen surface. 16,17) Figure 6(a) shows the ECCI micrograph of 50%-deformed austenite in the Fe-25Ni-0.5C alloy. In most of the γ grains, the microband structures are formed along either the primary or secondary slip planes in γ for uniaxial compression.…”

Section: Discussionmentioning

confidence: 99%

Comparison of Variant Selection between Lenticular and Lath Martensite Transformed from Deformed Austenite

Chiba

Miyamoto

2013

ISIJ Int.

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A variant selection of ausformed lath martensite in an Fe-9Mn alloy (MS = 602 K) and ausformed lenticular martensite in an Fe-25Ni-0.5C alloy (MS = 220 K) are compared quantitatively using EBSD measurements combined with a method for the reconstruction of austenite orientation. Differences were found in the selected variants by ausforming between those two martensite morphologies. In ausformed lath martensite, variants with habit planes parallel to the active slip planes in austenite were preferentially selected. This variant selection in lath martensite may be attributed to the preferential nucleation on the microband structures in austenite and lack of growth inhibition from the microband boundaries. On the other hand, in ausformed lenticular martensite, variants with habit planes parallel to the compression plane were preferentially selected. The reason for this is that lenticular martensite whose habit plane is parallel to the compression plane can grow easily in austenite grains elongated along the compression plane. This means fewer disturbances for those variants to grow with a habit plane parallel to the compression plane than for other variants.

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Section: Discussionmentioning

confidence: 99%

Comparison of Variant Selection between Lenticular and Lath Martensite Transformed from Deformed Austenite

Chiba

Miyamoto

2013

ISIJ Int.

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“…In this way, the entire grain structure of a selected region can be mapped. [11][12][13] The technique is being increasingly used for grain size determination and, while it unlikely to supplant established optical techniques due to the time-consuming nature of specimen preparation and the limited size of the area analysed, it can be invaluable in materials where standard optical techniques prove difficult to apply or where details of misorientation are required. It is difficult to apply optical analysis to Mg(Al) alloys in the as-cast state and previous attempts to use EBSD for these alloys have not been successful (but see Ref.…”

Section: Introductionmentioning

confidence: 99%

Grain Size Measurements in Mg-Al High Pressure Die Castings Using Electron Back-Scattered Diffraction (EBSD)

et al. 2004

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Optical metallographic techniques for grain-size measurement give unreliable results for high pressure diecast Mg-Al alloys and electron back-scattered diffraction mapping (EBSD) provides a good tool for improving the quality of these measurements. An application of EBSD mapping to this question is described, and data for some castings are presented. Ion-beam milling was needed to prepare suitable samples, and this technique is detailed. As is well-known for high pressure die castings, the grain size distribution comprises at least two populations. The mean grain size of the fine-grained population was similar in both AZ91 and AM60 and in two casting thicknesses (2 mm and 5 mm) and, contrary to previously published reports, it did not vary with depth below the surface.

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“…In an ECC image, the brightness variation (contrast) within each individual grain represents the variation in orientation. As the change in orientation within a single grain could be the result of deformation, this method has been established to study deformation in materials [13]. Fig.…”

Section: Crack Tip Deformationmentioning

confidence: 99%

Mechanisms of dwell fatigue crack growth in an advanced nickel disc alloy RR1000

Hardy

et al. 2014

MATEC Web of Conferences

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Abstract. RR1000 is one of an advanced class of nickel-based superalloys developed for disc applications. Under one hour dwell fatigue loading, complex crack growth behaviour has been observed especially in a coarse grained version of this alloy. At a temperature of 700 • C in air an increase of nearly two orders of magnitude in crack growth rates compared to baseline fatigue crack growth rates may be seen. However for certain microstructural conditions, cracks can also demonstrate retardation following initial acceleration. When using a direct current potential difference (d.c.p.d) technique for monitoring crack growth, a damage zone of a few hundred microns is often measured ahead of a fast growing crack. Advanced characterisation techniques including SEM, ECCI and X-ray tomography have been adopted in the current study to understand the observed damage zone and retardation phenomenon. It is found that damage zones measured by d.c.p.d reflect brittle and non-uniform advance of the crack resulting from continuous dynamic or quasi-dynamic fracture of an oxide intrusion ahead of the crack tip during the dwell period. In contrast, cracking of the oxide intrusion is less frequent or even prevented during dwell periods associated with a retarded and slow growing crack. Crack tip stress relaxation plays an important role in dictating whether or not dynamic cracking of the oxide intrusion can be avoided.

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Electron diffraction based techniques in scanning electron microscopy of bulk materials

Cited by 298 publications

References 85 publications

Comparison of Variant Selection between Lenticular and Lath Martensite Transformed from Deformed Austenite

Comparison of Variant Selection between Lenticular and Lath Martensite Transformed from Deformed Austenite

Grain Size Measurements in Mg-Al High Pressure Die Castings Using Electron Back-Scattered Diffraction (EBSD)

Mechanisms of dwell fatigue crack growth in an advanced nickel disc alloy RR1000

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