Engineering topics

Barabash, Rozaliya I

Publications and source records attributed to Barabash, Rozaliya I.

2 records

DOE OSTI2011

Cyclic-loading-induced Accumulation of Geometrically Necessary Dislocations Near Grain Boundaries in an Ni-based Superalloy

In this study, the fatigue-induced microstructure produced in a nickel-based polycrystalline superalloy that was subjected to cyclic loading was characterized by polychromatic x-ray microdiffraction (PXM) together with in-situ neutron diffraction and transmission-electron microscopy (TEM). In-situ neutron-diffraction measurements reveal two distinct stages of the fatigue damage: cyclic hardening followed by cyclic softening. Three-dimensional spatially resolved PXM micro-Laue measurements find an increase in the density of geometrically necessary dislocations near the grain boundaries, which is accompanied by lattice rotations and grain subdivisions. The PXM results are in agreement with the in-situ neutron-diffraction and TEM results.

36 MATERIALS SCIENCE↗

DOE OSTI2010

Diffuse X-ray scattering from tiny sample volumes

The emergence of intense synchrotron X-ray sources, efficient focusing optics and high-performance X-ray sensitive area detectors allows for measurements of diffuse scattering from cubic micron-scale sample volumes. Here we present an experiment that illustrates methods for studying the local structure and defect content of tiny sample volumes. In the experiment, an X-ray microbeam illuminating about {approx}5 {micro}m{sup 3} of a Ni-based superalloy single crystal, is used to collect Laue patterns and reciprocal space volume maps around fundamental and a superstructure reflections. This measurement illustrates how diffuse reciprocal-space distributions can be collected with good spatial and momentum-transfer resolution from a tiny real-space sample volume. This example demonstrates that emerging diffuse scattering techniques can provide fundamentally new information about crystallographic organization and defect content over many length scales.

36 MATERIALS SCIENCE↗