Deformation of Aluminum Investigated by Digital Image Correlation: Evidence of Simultaneous Crystal Slip and Grain Boundary Sliding

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Physical metallurgy and materials science, 2024-06, Vol.55 (6), p.1814-1835
• Main Authors: Dimanov, A., El Sabbagh, A., Raphanel, J., Bornert, M., Thien-Nga, L., Hallais, S., Tanguy, A.
• Format: Article
• Language: English
• Subjects: Aluminum; Anisotropy; Characterization and Evaluation of Materials; Chemistry and Materials Science; Crystals; Digital imaging; Engineering Sciences; Field tests; Grain boundaries; Grain boundary sliding; Grains; Image compression; Materials Science; Mechanical tests; Metallic Materials; Nanotechnology; Original Research Article; Physics; Plastic properties; Room temperature; Strain localization; Structural Materials; Surfaces and Interfaces; Thin Films
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-024-07349-0

We investigate the multiscale micromechanical behavior of nearly pure polycrystalline aluminum exhibiting randomly oriented coarse grains (ca. 300  μ m in size) between room temperature and 400 °C. We present the results from in situ mechanical testing obtained through scanning electron microscopy and full-field strain measurements by digital image correlation (DIC) during uniaxial compression, with controlled displacement rate. Direct observation of the process of developing strain heterogeneities allows for identification of the active mechanisms, characterization of their interactions, and quantification of their respective contributions to the overall strain. The full-field strain measurements were carried out, from the sample scale, to the scales of the aggregate of grains, and finally the single grain. DIC analysis was performed thanks to specific surface marking patterns obtained by electron microlithography appropriate for the different scales of interest. The strain localization patterns showed dominant crystal plasticity. Except at room temperature, we always observed simultaneous and continuous activity of grain boundary sliding, whose relative contribution increased with temperature. We suggest that for coarse-grained microstructures, grain boundary sliding acts as a complementary mechanism for the accommodation of local plastic incompatibilities inherent to the anisotropy of crystal plasticity.