In-situ study of planar slip in a commercial aluminum-lithium alloy using high energy X-ray diffraction microscopy

Wesley A. Tayon, Kelly E. Nygren, Roy E. Crooks, Darren C. Pagan

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


Aluminum-lithium alloys offer high specific-strength and -stiffness which makes them attractive for aerospace applications. However, several material related challenges have limited the use of these alloys including a tendency for grain boundary cracking due to localized damage known as delamination. Prior studies of these alloys have found evidence of a relationship between delamination and the occurrence of intense planar slip due to the shearing of the δ' (Al3Li) precipitate phase. In this study, far-field high-energy X-ray diffraction microscopy is used to quantify the effects of slip activity and subsequent stress response of the Al-Cu-Li alloy (AA2099) in both individual grains and various grain populations. Results show that grains with high Schmid factors, interpreted as an indicator of propensity for single slip at the elastic-plastic transition, are most likely to undergo grain softening consistent with precipitate-shear-driven planar slip. Conversely, grains with low Schmid factors are less prone to this deformation mode. A corresponding rise in triaxiality is found in grains which soften. The implications of pairings of grains exhibiting dissimilar micromechanical behaviors for delamination are discussed.

Original languageEnglish (US)
Pages (from-to)231-241
Number of pages11
JournalActa Materialia
StatePublished - Jul 2019

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys


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