Formation of brass-type shear bands and their influence on orientation changes of Cu-2%Al alloy {112}<111> single crystals

Abstract

Single crystals of the low stacking fault energy Cu-2%Al alloy, with initial orientation {112}<111>, have been deformed by compression in a channel die at 77 and 293 K. Microstructural and microtextural aspects of the formed brass-type shear bands were analyzed. Experimental techniques included TEM, SEM, optical microscopy together with SEM/EBSD and TEM/CBED microtexture measurements. The crystals first rotate by slip, then transform their orientation by deformation twinning. As shear banding starts, a strong increase of intensities near the Goss {110}<100> position is observed, and this process is connected with the rotation of twin lamellae within shear bands. At the TEM scale a second weaker component is noticed. Outside the bands, the twin-matrix lamellae rotate differently and the material reorients to {111}<112>.