Grain boundary structure in Al-Mg and Al-Mg-Sc alloys after equal-channel pressing

Oh-ishi, Keiichiro, Horita, Zenji, Smith, David J. and Langdon, Terence G. (2001) Grain boundary structure in Al-Mg and Al-Mg-Sc alloys after equal-channel pressing. Journal of Materials Research, 16, 583-589.

Abstract

Samples of an Al-3% Mg alloy and an Al-3% Mg-0.2% Sc alloy were subjected to equal-channel angular pressing (ECAP) to reduce the grain size to approximately 0.2-0.3 ìm. Some samples of each alloy were also annealed for 1 h at temperatures of either 423 or 673 K, respectively. High-resolution electron microscopy was used to examine the microstructure both before and after annealing. The grain boundaries after ECAP were wavy and faceted and in high-energy nonequilibrium configurations. These results were consistent with earlier observations of materials subjected to severe plastic deformation using high-pressure torsion. In addition, some grain boundaries in the Al-Mg-Sc alloy had a zigzag appearance after annealing at 673 K, where the straight portions of the boundary were identified as low-energy {111} planes. It is suggested these are mobile boundaries lying in a lowest energy configuration where mobility may be restricted by the presence of incoherent Al3Sc particles.

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Contributors

Author: Terence G. Langdon

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