Characterization of Casting Defects in the Single Crystal Turbine Blade Airfoil

Abstract

In the paper turbine blades made from single crystal CMSX-4 superalloy were investigated by X-ray diffraction methods (topography, Ω -scan mapping) complemented by scanning electron microscopy observations. By the X-ray diffraction topography method several misorientation defects were visualized as well as dendrites arrangement. It was discussed that tip of the airfoil and thin walled area of the turbine blades located near the trailing edge can accumulate more growth defects than other airfoil part, due to the complex shape of the mould.

Subgrain boundaries in single crystal blade airfoil of aircraft engine

“…Cross‐section IV were prepared near the tip of the blade, what assumedly allows to determine all low‐angle boundaries, created during dendritic crystallization in the airfoil. The boundary surfaces are approximately parallel to the Z axis (Figure a), therefore low‐angle boundary, created during crystallization, may extend along crystallization direction and pass through the whole airfoil.…”