As cast single -crystal turbine blade roots made of CMSX-4 were investigated. The Laue method, X-ray diffraction topography, novel X-ray cliffractometer provided by EEG company and scanning electron microscopy were applied to study the subgrain structure. ft was found that low angle boundaries of macro scale length were present in the roots of the blades. Additionally, linear distributions of angles describing inclination of [001]gamma direction to the main blade axis and rotation of this direction were defined across the low angle boundaries by EFG diffractometer. With the use of this diffractometer, the lattice parameter linear distributions across the low angle boundaries were also defined. The dendrites at were determined by scanning electron microscopy (SEM) macro images. The mechanism of the formation of subgrain boundaries and characteristics of the orientation interactions between dendrites inside subgrains were proposed. (C) 2013 Elsevier B.V. All rights reserved