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As-cast single-crystal turbine blade roots made of CMSX-4 were investigated. The Laue method, X-ray diffraction topography, novel X-ray diffractometer provided by EFG company and scanning electron microscopy were applied to study the subgrain structure. It 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]γ' 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 arrangement 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. [ABSTRACT FROM AUTHOR]

This study focuses on the evaluation of the crystal structure perfection in the single crystal made of CMSX-4 nickel superalloy and its effect on creep resistance. Single crystal castings were manufactured by directional solidification process at the withdrawal rate of 1, 3, 5 and 7 mm/min. Light (LM) and electron (SEM, TEM) microscopy, X-ray diffraction and Mossbauer spectroscopy were used for evaluation of the microstructure and crystal structure perfection. Castings were also subjected to creep tests. The best creep resistance was obtained for the casting manufactured at the withdrawal rate of 3 mm/min, characterized by the highest crystal structure perfection compared to the other castings examined. [ABSTRACT FROM AUTHOR]