In certain orientations, Al-Li 2090 T8E41 cracks more slowly in fatigue than other aluminum alloys due to roughness-induced closure linked to the average texture or macrotexture. For this application, three-dimensional, non-destructive measurement of microtexture and strain evolution within samples was developed using synchrotron polychromatic X-ray microbeam diffraction; its use in mapping the microtexture of fatigue crack asperities in Al-Li 2090 are reported. Groups of adjacent grains with nearly identical orientations were found at numerous locations in the plate centers, and this type of "mesotexture" appeared closely tied to asperity formation. Changing arrangements of 111 diffraction spots relative to the samples' rolling and crack propagation directions are found to correspond to the transitions between a relatively planar section of the crack and an adjacent asperity.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Polymers and Plastics
- Metals and Alloys