Comparative Study on Microstructural Stability of Pre-annealed Electrodeposited Nanocrystalline Nickel During Pack Rolling

Abstract

Microstructural stability is an important issue for nanocrystalline materials to be practically used in many fields. The present work shows how microstructure evolves with rolling strain in pre-annealed electrodeposited nanocrystalline nickel containing an initial strong fiber texture, on the basis of X-ray diffraction line profile analysis as well as transmission electron microscopy observation. The influence of shear strain on microstructural stability of the metal/roll contact interface is compared with that of the metal/metal contact interface; the latter would be closer to deformation in plane strain compression. From the statistical microstructural information, together with experimentally observed microstructure of deformed grains after the final rolling pass, it seems fair to conclude that the microstructure of the metal/metal contact interface is more stable during pack rolling than that of the metal/roll interface.

Grain Orientation Induced Softening in Electrodeposited Gradient Nanostructured Nickel during Cold Rolling Deformation

“…In particular, grain size, dislocation density and stacking fault probability for the undeformed and final deformed layers for the gradient samples are determined and summarized in Table 1. Based on our previous investigation of the microstructure of cold-rolled nanostructured nickel [20,21], FWHM variation is mainly influenced by grain size and dislocation density. With increasing rolling strain, an increase in the FWHM of the (111) diffraction peak is found in the majority of the deformed layers.…”

“…Furthermore, the effect of two different stress states on deformation behavior is also revealed by the change rate of I 111 /I 200 . On the whole, since the surface layers simultaneously undergo compression and shear deformation [21,28], the surface or near surface layers exhibit a relatively higher variation ratio of I 111 /I 200 . For the center layer, it would be closer to deformation in plane strain compression [21,29], the preferential (200) orientation is relatively weak.…”