Microstructural characterization of nickel subjected to dynamic plastic deformation

Abstract

Average microstructural parameters and the extent of microstructural heterogeneity in nickel deformed at a high strain rate have been characterized quantitatively and compared to those after compression at a quasi-static strain rate. The microstructure in the high strain rate sample was found to be more refined and less heterogeneous than that in the sample compressed at a low strain rate. The greater refinement in the former sample was achieved due to subdivision by a high frequency of finely-spaced low-angle boundaries.

Analysis of through-thickness heterogeneities of microstructure and texture in nickel after accumulative roll bonding

“…This approach has been previously applied for characterizing heterogeneity in microstructural refinement in samples deformed to large strains by either equal channel angular extrusion (ECAE) or compression [18][19][20][21]. The partitioning is based on the idea of detecting continuous areas within an EBSD map that have not been subdivided by boundaries of large misorientation angles, and such areas represent a heterogeneity in the effective refinement of the deformed microstructure.…”

“…Moreover, it has recently been shown [18] that the HAB fraction and the average boundary spacing do not always provide a good description of the extent of heterogeneity within a heavily deformed microstructure. In contrast, it has been demonstrated that partitioning of a deformed microstructure into subsets that contain either predominantly low angle misorientations or predominantly high angle misorientations can be used to provide a better quantitative characterization of microstructural heterogeneities in heavily deformed metals [18][19][20][21]. This approach is applied in the present work, where the microstructure and texture are examined over a large number of locations across the thickness of a nickel sample after 6 ARB cycles.…”

Oxide dispersion-strengthened steel PM2000 after dynamic plastic deformation: nanostructure and annealing behaviour

“…For instance, a lamellar structure with a boundary spacing of only 0.1 lm developed in a modified 9Cr-1Mo steel (T91) [8] due to compression via dynamic plastic deformation (DPD) [9] to a strain of 2.3 at a strain rate of 10 2 -10 3 s -1 . A more effective structural refinement by DPD as compared to lowstrain-rate deformation has also been documented for other metals such as aluminium and nickel [10,11]. It is reasonable to expect that DPD can also be very effective in refining the microstructures of ODS steels.…”

Microstructural Analysis of Orientation-Dependent Recovery and Recrystallization in a Modified 9Cr-1Mo Steel Deformed by Compression at a High Strain Rate

“…Structural Refinement During DPD DPD has previously been shown to result in more pronounced structural refinement than deformation at low strain rates, which has been attributed to a higher density of dislocations forming more finely spaced dislocation boundaries than in materials after QSC. [3,21,22] Although the microstructure of the QSC sample deformed to a strain of 2.3 has not been characterized in the present work, the hardness data available after this strain indicate that the QSC sample is considerably softer (348 HV1) than the DPD sample (365 HV1), which is consistent with earlier observations for the samples deformed to a lower strain [3] and which suggests that the structural refinement by DPD is more effective than that by QSC also at a strain of 2.3. Compared to a previous study of the present material DPD-processed to a strain of 0.5, [3,7] where a dislocation cell structure was observed to have an average boundary spacing of 0.2 lm, the sample studied in the present work contains a much more refined lamellar structure with a boundary spacing of only 0.1 lm.…”