Using Electron Backscatter Diffraction (EBSD) to Measure Misorientation between ‘Parent’ and ‘Daughter’ Grains. Implications for Recrystallisation and Nucleation

Abstract:

Electron backscatter diffraction (EBSD) is an extremely valuable tool, as it measures full crystallographic orientation information. This technique has been used to measure the statistics of misorientations between original ‘parent’ grains and recrystallised ‘daughter’ grains in a mylonitic quartzite. The angle of misorientation has implications on the controlling recrystallisation mechanism. The sample is a natural mylonitic quartzite collected from the stack of Glencoul, NW Scotland. The sample exhibits a common partially recrystallised microstructure. The data shows the average misorientations between the ‘parent’ and ‘daughter’ grains are 30º, this value seems too high for only subgrain rotation recrystallisation to be taking place. Moreover there is no gradation in the boundary misorientation from the internal substructure of the ‘parent’ grain to the ‘daughter’ grains. The internal substructure size of the ‘parent’ grain is bigger than the size of the ‘daughter’ grains. For subgrain rotation recrystallisation you may expect to see a core and mantle structure and for the ‘daughter’ grains’ to be of similar size to the internal substructure of the ‘parent’ grain. Another mechanism has either controlled the recrystallisation altogether or has become active after subgrain rotation had taken place and modified the microstructure.

• Periodical: Materials Science Forum (Volumes 467-470)
• Pages: 573-578
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.467-470.573
• Online since: October 2004
• Authors: Angela Halfpenny, David J. Prior, John Wheeler
• Keywords: Electron Backscatter Diffraction (EBSD), Misorientation, Recrystallization

References

[1] C.W. Passchier and R.A.J. Trouw, Microtectonics. 2nd ed. 1996, Berlin Heidelberg New York: Springer-Verlag. 289.

[2] J.L. Urai, W.D. Means, and G.S. Lister, Dynamic recrystallisation of minerals. Geophysical Monograph, 1986. 36(The Paterson Volume): pp.161-199.

[3] J. Wheeler, et al., The petrological significance of misorientations between grains. Contributions to mineralogy and petrology, 2001. 141: pp.109-124.

DOI: 10.1007/s004100000225

[4] D.J. Prior, et al., The application of electron backscatter diffraction and orientation contrast imaging in the SEM to textural problems in rocks. American Mineralogist, 1999. 84: pp.1741-1759.

DOI: 10.2138/am-1999-11-1204

[5] R.D. Law, Heterogenous deformation and quartz crystallographic fabric transitions: natural examples from the moine thrust zone at the stack of Glencoul, northern Assynt. Journal of Structural Geology, 1987. 9(2): pp.001-015.

DOI: 10.1016/0191-8141(87)90083-6

[6] R.D. Law, M. Casey, and R.J. Knipe, Kinematic and tectonic significance of microstructures and crystallographic fabrics within quartz mylonites from the Assynt and Eriboll regions of the Moine thrust zone, NW Scotland. Transactions of the Royal Society of Edinburgh, 1986. 77: pp.99-125.

DOI: 10.1017/s0263593300010774

[7] G.E. Lloyd, C.C. Ferguson, and R.D. Law, Discriminatory petrofabric analysis of quartz rocks using SEM electron channelling. Tectonophysics, 1987. 135: pp.243-249.

DOI: 10.1016/0040-1951(87)90165-x