Grain orientation and dislocation patterns

Abstract

Dislocation patterns have been characterized by transmission electron microscopy and Kikuchi line analysis in pure, polycrystalline aluminium deformed in tension at room temperature in the strain range 0.05–0.34. The angle strain relationship of the dislocation boundaries, their scaling behaviour and the occurrence of similitude show that two dislocation patterns coexist in all grains, albeit, with very different characteristics, dependent on the grain orientation. An analysis of the hardening behaviour of the grains in the polycrystal and a comparison with single crystal behaviour show a similar strong correlation, pointing to the slip pattern as a dominating factor both behind the microstructural evolution and the hardening. The division of the stereographic triangle representing all possible crystallographic orientations at the tensile axis based on microstructural characterization and hardening behaviour, correlates with a division based on slip pattern characteristics.

Acknowledgement

The authors gratefully acknowledge the Danish National Research Foundation for supporting the Center for Fundamental Research: Metal Structures in Four Dimensions, within which this work was performed. Discussions with A. Godfrey, D. A. Hughes, D. Juul Jensen, Q. Liu, B. Ralph and J. A. Wert are gratefully acknowledged. A special thanks to Eva Nielsen for assistance with the manuscript.