Amorphous Intergranular Film Effect on the Texture and Structural Evolution During Cold-Rolling of Nanocrystalline Ni-Zr Alloys

The presence of amorphous intergranular films (AIFs) in nanocrystalline (NC) metals improves the mechanical properties and thermal stability. However, their influence on the overall deformation behavior of bulk nanostructured materials during the fabrication process is still unexplored. Here, we investigate the texture and defect evolution along with the stress distribution in NC Ni specimens with ordered grain boundaries (GBs), 50 pct AIFs, and 100 pct AIFs during the cold-rolling process. Results from the orientation analysis and texture plots reveal that samples with only traditional ordered GBs show stress-induced grain growth, whereas the presence of AIFs reduces extensive grain rotations and boundary movements. Findings from the atomic stress analysis also indicate tensile residual stress in specimen with amorphous films due to the anisotropic grain elongation without significant grain growth. Further, amorphous films also aid in confinement of dislocations near the surface of the specimens and annihilation of defects in the center grains, thus generating a harder surface and a softer core. (C) The Minerals, Metals & Materials Society and ASM International 2022

Automated summary

The presence of amorphous intergranular films in NC Ni specimens affects the deformation behavior during the fabrication process, reducing grain rotations and boundary movements while generating a harder surface and softer core.