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Title: Shear-Coupled Grain Growth and Texture Development in a Nanocrystalline Ni-Fe Alloy during Cold Rolling

Abstract

The evolution of texture, grain size, grain shape, dislocation and twin density has been determined by synchrotron X-ray diffraction and line profile analysis in a nanocrystalline Ni- Fe alloy after cold rolling along different directions related to the initial fiber and the long axis of grains. The texture evolution has been simulated by the Taylor-type relaxed constraints viscoplastic polycrystal model. The simulations were based on the activity of partial dislocations in correlation with the experimental results of dislocation density determination. The concept of stress-induced shear-coupling is supported and strengthened by both the texture simulations and the experimentally determined evolution of the microstructure parameters. Grain-growth and texture evolution are shown to proceed by the shear-coupling mechanism supported by dislocation activity as long as the grain size is not smaller than about 20 nm.

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science - Office of Basic Energy Sciences - Scientific User Facilities Division
OSTI Identifier:
1392332
DOE Contract Number:
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science; Journal Volume: 47; Journal Issue: 12
Country of Publication:
United States
Language:
English
Subject:
Dislocation mechanism of grain growth; Texture simulation; X-ray line profile analysis; grain growth; nanocrystalline Ni-Fe alloy; strain-induced shear-coupling

Citation Formats

Li, Li, Ungár, Tamás, Toth, Laszlo S., Skrotzki, Werner, Wang, Yan Dong, Ren, Yang, Choo, Hahn, Fogarassy, Zsolt, Zhou, X. T., and Liaw, Peter K.. Shear-Coupled Grain Growth and Texture Development in a Nanocrystalline Ni-Fe Alloy during Cold Rolling. United States: N. p., 2016. Web. doi:10.1007/s11661-016-3753-7.
Li, Li, Ungár, Tamás, Toth, Laszlo S., Skrotzki, Werner, Wang, Yan Dong, Ren, Yang, Choo, Hahn, Fogarassy, Zsolt, Zhou, X. T., & Liaw, Peter K.. Shear-Coupled Grain Growth and Texture Development in a Nanocrystalline Ni-Fe Alloy during Cold Rolling. United States. doi:10.1007/s11661-016-3753-7.
Li, Li, Ungár, Tamás, Toth, Laszlo S., Skrotzki, Werner, Wang, Yan Dong, Ren, Yang, Choo, Hahn, Fogarassy, Zsolt, Zhou, X. T., and Liaw, Peter K.. 2016. "Shear-Coupled Grain Growth and Texture Development in a Nanocrystalline Ni-Fe Alloy during Cold Rolling". United States. doi:10.1007/s11661-016-3753-7.
@article{osti_1392332,
title = {Shear-Coupled Grain Growth and Texture Development in a Nanocrystalline Ni-Fe Alloy during Cold Rolling},
author = {Li, Li and Ungár, Tamás and Toth, Laszlo S. and Skrotzki, Werner and Wang, Yan Dong and Ren, Yang and Choo, Hahn and Fogarassy, Zsolt and Zhou, X. T. and Liaw, Peter K.},
abstractNote = {The evolution of texture, grain size, grain shape, dislocation and twin density has been determined by synchrotron X-ray diffraction and line profile analysis in a nanocrystalline Ni- Fe alloy after cold rolling along different directions related to the initial fiber and the long axis of grains. The texture evolution has been simulated by the Taylor-type relaxed constraints viscoplastic polycrystal model. The simulations were based on the activity of partial dislocations in correlation with the experimental results of dislocation density determination. The concept of stress-induced shear-coupling is supported and strengthened by both the texture simulations and the experimentally determined evolution of the microstructure parameters. Grain-growth and texture evolution are shown to proceed by the shear-coupling mechanism supported by dislocation activity as long as the grain size is not smaller than about 20 nm.},
doi = {10.1007/s11661-016-3753-7},
journal = {Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science},
number = 12,
volume = 47,
place = {United States},
year = 2016,
month = 9
}
  • Microstructures in nanocrystalline Ni-Fe alloys during cold rolling are quantitatively investigated by synchrotron high-energy X-ray diffraction. It is found that rolling leads to an obvious reduction in the densities of both dislocations and twins and an increase in crystallite size. A huge dislocation flux flows through the grains during rolling, even though only a small fraction remains in the specimen after rolling. A mechanically induced relaxation of the initial high-excited state of materials is revealed.
  • Stress softening after cold rolling is observed in an electrodeposited nanocrystalline Ni-Fe alloy. The grain-size distribution becomes much broader after the cold rolling. Microstructure changes, though moderate, such as simultaneously decreased dislocation and twin densities with grain growth during cold rolling, are systematically proved by synchrotron high-energy X-ray diffraction, and transmission-electron microscopy and differential-scanning calorimetry (DSC). The amorphous fractions in the form of grain boundaries are evidenced by the diffuse-background scatterings and large DSC values. Partial dislocation separation calculation, a dislocation mean free path and annihilation model, and texture development together reveal that the current nanocrystalline Ni-Fe alloy exhibits themore » combined behavior of perfect dislocation slip and grain-boundary mediated deformation.« less
  • A new trend in grain growth modeling is to consider the texture development during grain coarsening, and various statistical models have been developed (Novikov, Bunge, Abbruzzese/Luecke) for this purpose. For the case of texture changes during grain growth all these models predict different growth kinetics for the grains of different texture components. This means that the average grain sizes for grains of different orientations should be different. Strong texture changes have been observed during grain growth for instance in CuZn, AlMn and AlMg alloys. However, the average grain sizes for grains of different orientations have not been investigated experimentally yet.more » This was the aim of the present work. Isothermal grain growth of {alpha}-brass and copper were analyzed by optical microscopy, neutron diffraction and EBSP-measurements (Electron Backscattering Pattern). The EBSP-technique was used to separate the average grain sizes and the grain size distributions of the main texture components in both materials. It was found that the average grain size of grains of different orientations in the investigated materials are statistically significant different, and the results are discussed with reference to the statistical models mentioned above.« less
  • In this paper, the microstructure and texture evolution during annealing of rolled Mg alloy AZ31B, at temperatures ranging from 260 to 450°C, is characterized, and a grain growth exponent of n=5, indicating inhibition of grain growth, is observed. Broadening of the normalized grain size distributions, which indicates abnormal grain growth, was observed at all temperatures investigated. It is shown, using a Zener-type analysis for pinning of grain boundaries by particles, that impurity-based particles are responsible for grain growth inhibition and abnormal grain growth. The strong basal texture which develops during rolling of the Mg alloy, resulting in an initial peakmore » intensity in the (0002) pole figure of nine multiples of a random distribution (MRD), increases to ~15 MRD during annealing at 400 and 450°C. Furthermore, a specific texture component {0001}(1120) is observed in the orientation distribution, which increases from 10 to 23 MRD at 400°C. It is hypothesized that the anisotropic grain boundary properties (i.e. low angle boundaries have low energy and mobility) are responsible for the texture strengthening. Additionally, electron backscattered diffraction reveals the recrystallized microstructure to contain a significant number of boundaries with ~30° misorientation about the <0001> direction, and this boundary type persists throughout most annealing treatments explored.« less