Techniques for the measurement of local pole figures in the Transmission Electron Microscope (TEM)
are summarized and applications to deformed aluminum are given. Local pole figures are obtained by
measuring the intensity distribution along ring patterns in Selected Area Diffraction (SAD) separately
for various tilts of the specimen with respect to the incident electron beam. The computer control of
the TEM allows a data acquisition in reasonable time. The measured intensities are corrected either
experimentally or analytically for the increase of sampled volume and for the increased absorption
with increasing tilt angle of the specimen. The application of orientation distribution functions (ODF)
using the series expansion technique in conjunction with the positivity method allows a quantitative
texture analysis of the pole figures.

Hasso Weiland

S. Panchanadeeswaran

Local Pole Figures in the Tem&#x2014; Measurement and ODF Determination

This paper discusses how microtexture data, i.e. individual orientations which are measured on a grain
and environmentally specific basis, are applied to grain boundary geometrical parameters. Three main
areas are addressed: the &#x201C;interface-plane&#x201D; scheme for specifying the five degress of freedom of a
boundary, comparisons of experimental techniques for data collection, and representation of grain
boundary misorientations in Rodrigues-Frank space. Particular attention is paid to electron
back-scatter diffraction as a method of probing grain boundary misorientation and the crystallographic
orientation of the grain boundary plane.

Valerie Randle

Application of Microtexture Measurements in the SEM to Grain Boundary Parameters

The development of microstructure, texture, misorientation and grain boundary character during
cyclic deformation of Nickel at elevated temperatures was investigated. At high numbers of cycles
grain boundaries align with the maximum shear stress. Texture and microstructure change significantly
and low &#x2211;CSL boundaries with (111) rotation axes emerge. The Schmid factor increases with
progressing deformation but Sachs- and Taylor-type deformation modelling fail to predict the actual
texture change. It is proposed to attribute the observed texture and microstructure development to an
interaction of deformation mechanisms with grain boundary motion.

S. Brodesser

G. Gottstein

Microstructure and Microtexture Evolution During High Temperature Low Cycle Fatigue of Nickel

The yield strength anisotropy of aluminum-lithium sheet is known to be strongly dependent on
crystallographic texture and grain morphology. In this study, the microstructure and texture of
unrecrystallized and recrystallized variants of 2090 were examined in an SEM, using a combination of
backscattered electron imaging and Kikuchi patterns. Local orientation measurements both through
the sheet thickness and parallel to the rolling direction were used to determine the degree of
misorientation between nearest-neighbor grains. Yield strength predictions based on the spatially
resolved texture measurements show that the course, recrystallized grains have reduced in-plane and
through-thickness anisotropy compared to the unrecrystallized structure.

S. M. Miyasato

J. Liu

F. Barlat

Spatially Resolved Texture Analysis of Aluminum-Lithium Sheet

The recrystallization mechanisms in deformed aluminium single crystals have been investigated by
SEM microdiffraction techniques (ECP and EBSP). Aluminium crystals of (001)(uv0) and (001)[01<mml:math id="E1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover><mml:mn>1</mml:mn><mml:mo>&#x2D;</mml:mo></mml:mover></mml:mrow></mml:math>]
orientations were deformed in plane strain compression to a true strain of &#x7E;1 to develop different
deformation microstructures. Transition bands separating deformation bands were formed by
orientation splitting in the (001)(uv0) crystals, but were not observed in the (001)[01<mml:math id="E2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover><mml:mn>1</mml:mn><mml:mo>&#x2D;</mml:mo></mml:mover></mml:mrow></mml:math>] crystal.During annealing at 250&#xB0;C and 400&#xB0;C, recrystallization nuclei are developed in both the deformed
matrix and along transition bands. Matrix nucleation appears to occur by a subgrain coalescence
mechanism according to which the new grains are misoriented 15-30&#xB0; from the average as-deformed
material. Transition band nucleation gives an orientation spread 20-30&#xB0; around the original,
undeformed crystal orientation. A well-defined cube recrystallization texture is obtained at 400&#xB0;C
after complete recrystallization of the initial cube crystal.

A. Akef

J. H. Driver

Local Textures in Deformed and Recrystallized Aluminium Crystal

The Orientation Distribution Function (O.D.F.) calculation is usually performed using pole figures
measured by X-ray or neutron diffraction. However, this kind of experimental technique does not
allow to determine a total ODF since the odd terms of the series expansion are not directly accessible
from pole figures. The individual orientation measurement technique can be used but it is necessary to
estimate the right orientation number necessary to calculate a statistically reliable ODF. For samples
at the surface, at the fifth of the thickness from the surface and at the centre of a Fe 3&#x25; Si sheet, the
present study shows that only 100 orientations are sufficient to find the main components of the
texture but this number must be increased by a factor 10 to evaluate with a rather good accuracy the
height of the peaks. In the case of a titanium alloy so called TA6V 350 orientations appear to be
sufficient.

R. Penelle

T. Baudin

Microtexture Characterization by EBSP in Iron and Titanium Alloys

A completely automated system which couples automatic analysis of electron backscatter diffraction
patterns (EBSPs) with precise movement of the sample in the SEM is described. The Hough
transform is implemented into an existing technique for identifying lattice orientation through
automatic analysis of EBSPs. The ability of the Hough transform approach to correctly identify
diffraction bands is quantitatively compared with the Burns algorithm. Both methods were tested on
1000 EBSPs from well annealed oxygen-free, electrical grade (OFE) copper, 120 patterns from as-cast
commercially pure aluminum and 106 patterns from 40&#x25; channel-die compressed aluminum. Only
slight differences were found in the ability of the methods to correctly identify bands in the sample
EBSPs. The three test runs resulted in 95-99&#x25; (OFE Cu), 97.5-99&#x25; (as-cast AI) and 81-85&#x25;
(deformed AI) correctly determined orientations (less than 5&#xB0; off the manually determined reference
orientations). The limits in the ability of the band detection algorithms to fix the bands exactly are
discussed. To obtain the orientation which satisfies the detected bands most completely, a method of
averaging solutions obtained from different triplets of bands is introduced.

K. Kunze

S. I. Wright

B. L. Adams

D. J. Dingley

Advances in Automatic EBSP Single Orientation Measurements

Single crystals and polycrystals of aluminium containing non-deformable second-phase particles of
silicon, have been deformed, and the resultant structures investigated by microscopy and by X-ray and
microtexture techniques. The particle size is found to influence the scale of the deformation bands
formed, and there is evidence that particles may affect the nucleation of these bands. The deformed
materials were recrystallized, and the effect of particle stimulated nucleation on the weakening of the
rolling texture is discussed with reference to a computer simulation. In contrast, the recrystallization
texture of particle-containing single crystals deformed on only two slip systems is sharp, and it is
shown that the texture components are consistent with plasticity theory.

F. Habiby

F. J. Humphreys

A Microstructure Investigation of the Deformation and Recrystallization of Particle-Containing Aluminium-Silicon Alloys

The potential of local texture techniques for investigations of recrystallization are reviewed. The need
for automatization of such techniques is discussed. It is shown how orientation measurements using
one of these techniques, the electron back scattering pattern (EBSP) technique, can be made fully
automatic.

D. Juul Jensen

Automatic EBSP Analysis for Recrystallization Studies

Brent L.  Adams

Editorial Comments on the Symposium on Microscale Textures of
Materials 21-23 October 1991, Cincinnati

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