An interface compatibility/equilibrium mechanism for delamination fracture in aluminum-lithium alloys

M. C. Messner, A. J. Beaudoin, R. H. Dodds

Research output: Contribution to journalArticlepeer-review


This work describes a mechanism for the initiation of delamination cracks in Al-Li alloys based on the soft/stiff character of adjacent grains. Small-scale-yielding, crystal plasticity simulations of divider grain configurations (L-T) reveal an elevated mean stress on grain boundaries. This mean stress increase drives a sharp localization of the Rice-Tracey parameter to the grain boundaries - elevation of the RT parameter indicates favorable conditions for void growth and triggering of delamination cracking, in agreement with the fractography of Ritchie and co-workers. Our simulation results and available experimental evidence indicate delamination initiates typically between soft/stiff grain pairs, often Bs (Bunge-convention Euler angles ϕ1=131°, Φ=83°, ϕ2=307°) or S (ϕ1=233°, Φ=151°, ϕ2=105°) orientations. The crystal plasticity results and a simple model of a soft/stiff material interface show that mean stress accumulation is a consequence of the mechanics of such an interface, and not necessarily tied to material inhomogeneities near the GBs (such as precipitate free zones).

Original languageEnglish (US)
Pages (from-to)70-84
Number of pages15
JournalEngineering Fracture Mechanics
StatePublished - Jan 1 2015


  • Aerospace vehicles
  • Aluminum alloys
  • Delamination
  • Intergranular fracture
  • Micromechanics

ASJC Scopus subject areas

  • General Materials Science
  • Mechanics of Materials
  • Mechanical Engineering


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