Neutron and synchrotron X-ray diffractions were used to study the texture development in the face-centered-cubic nickel-based superalloy over gauge volumes ranging from hundreds of cubic millimeters down to sub-cubic micrometers. The bulk averaged results find a uniform texture development from collective slip. However, X-ray microbeam studies at microscale find that the plastic deformation within a single grain is mediated by limited slip, as evidenced by the local strain distribution. Polychromatic microdiffraction shows the formation of several distinct structural zones even in the same grain. A hierarchical heterogeneous geometrically-necessary dislocations arrangement and distinct slip bands are observed within each grain. A depth-dependent change of the stereographic projection within the slip band in the grain is demonstrated. Correlated oscillations of the lattice orientation at the submicron scale evolve into an overall texture at the macroscale. Possible reasons for this observed structural evolution are discussed. (C) 2010 Elsevier B.V. All rights reserved.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING