ECCI analysis of shear accommodations at grain boundaries in commercially pure alpha titanium

• Published in: International journal of plasticity 2020-08, Vol.131 (C), p.102731, Article 102731
• Main Authors: Han, Songyang, Crimp, Martin A.
• Format: Article
• Language: English
• Subjects: Angles (geometry); Burgers vector; Channeling; Copper; ECCI; Edge dislocations; Grain boundaries; Misalignment; Polycrystalline deformation; Slip planes; Slip transfer
• ISSN: 0749-6419; 1879-2154
• DOI: 10.1016/j.ijplas.2020.102731

This study uses a novel approach that couples electron channeling contrast imaging (ECCI) with controlled removal of surface material to investigate the slip system/grain boundary interactions by assessing the geometry of slip planes and grain boundaries as a function of depth. The comparison of spacing, relative distributions, and correlations of slip bands across grain boundaries reveals surface biasing on the slip band behavior in the grain boundary region. Furthermore, using analysis of the compatibility factor m’, the Schmid factor of each slip system, and the angles ϴ between slip planes, a more comprehensive understanding of the details of the mechanisms of strain transfer and heterogeneous deformation is developed. In general, the misalignment of primary slip systems on the grain boundary planes necessitates the activation of secondary accommodating slip systems close to the grain boundary area that are better aligned (higher m’ and lower ϴ) with respect to the incoming slip system across the grain boundary. Such systems have the same Burgers vector as the primary slip systems within the respective grains, but are typically on low mobility slip planes. [Display omitted] •Slip trace analysis and ECCI were used to study slip band nature and distribution on the surface of deformed polycrystals.•Surface and subsurface observations reveal the free surface biases the nature of slip transfer.•Slip accommodation requires secondary slip systems if the slip bands do not have common intersections in the grain boundary.•Secondary and primary accommodating slip systems typically have the same Burgers vectors, but on different slip planes.•Slip transfer parameters were assessed based on the geometry of the slip bands and grain boundaries as a function of depth.