In March microstructural research on KoBo deformed materials continues. Two sample types of KoBo'ed hexagonall materials were prepared: 8 mm discs from CP Grade 2 titanium and resin immersed 2 mm zinc wires (oriented to observe transverse section). Samples were prepared for EBSD investigations. In case of titanium which has become stronger after KoBo deformation (675 Mpa compared to 345 MPa of standard CP grade 2 Ti) observed microstructure consisted of mixture of elongated twisted grains (length ~7 um) and smaller equiaxial grains (diameter ~1 um). Some initial problems with surface preparation for EBSD (lots of unsolved diffractions) were solved by use of thicker sample. This allowed for better control over polishing part of preparation and resulted with higher rate of indexed diffractions.
Other type of samples (pure zinc) where also investigated with EBSD technique. Microstucture consisted of smaller and larger equiaxed grains with dimensions grouped around 15 and 40 micrometers. Interesting observation was made during analysis of image quality factor. Distribution of qf (which can be connected to local strains related to crystallographic defects) suggests that zinc processed by KoBo technique poses composite like structure. This structure consists of undistorted grains and relatively thick areas along grain boundaries with high level of residual strain. Such an arrangement of features could be used to explain some of the unusual mechanical behavior observed in Zn KoBo.