Acoustic emission and changes in dislocation structure and magnetostriction accompanying plastic deformation of [126]-oriented Fe-Ga alloy single crystals

摘要

Controlled compressive deformation of [126]-oriented Fe-20 at. % Ga alloy single crystal along [126] direction results in large and asymmetric changes in the magnetostriction of the sample. This is in contrast to a much smaller change in magnetostriction observed in [100]-oriented single crystal deformed along [001] direction. Deformation of [126]-oriented crystal along [126] direction involved operation of only one of the slip systems. This is confirmed by TEM examination that showed only a single set of dislocation array which introduces asymmetric strain modulation in the crystal. The [100]-oriented crystal deformation involved operation of multiple slip systems and formation of several sets of dislocation arrays which introduce more symmetric strain modulations. The results suggest that the nature of strain modulation introduced by the dislocation arrays has a strong influence on the magnetostrictive behavior. Several sudden load drops accompanied by acoustic emissions and formation of slip bands were observed during [126]-oriented crystal deformation, while no such load drops or audible acoustic emissions were seen during the [001]-oriented crystal deformation.