Uniaxial tensile deformation of uranium 6 wt pct niobium: A neutron diffraction study of deformation twinning

Brown, Donald W.; Bourke, M.A.M.; Stout, M.G.; Dunn, P.S.; Field, Robert D.; Thoma, Dan J.

doi:10.1007/s11661-001-0197-4

Cited by 58 publications

(53 citation statements)

References 32 publications

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“…[1]. That twins result in significant strain hardening, in this case, only at strains beyond the plateau region, is well established in the metallurgical literature, in general, [58,59] and in Mg, in particular. [16,20,25,28,33,60] The relationship between the plateau and twinning is further enhanced by noting that neither Co [34] nor Ti 3 SiC 2 twin; neither exhibit a plateau.…”

Section: A Knementioning

confidence: 83%

“…The role of twinning in hardening is well appreciated in the metallurgical literature. [16,20,25,28,[58][59][60] When Agnew et al [24] studied the two other orientations, viz. IPT and TTC (Figures 2(a) and (c)), respectively, they found that twinning played a much more modest role in the deformation, especially at low deformation strains.…”

Section: B Correlation Between Kinking Bending and Twinningmentioning

confidence: 99%

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Kinking Nonlinear Elasticity and the Deformation of Magnesium

Zhou

Barsoum

2009

Metall Mater Trans A

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Despite a large body of work devoted to understanding the deformation of polycrystalline magnesium, there are still some outstanding questions, not the least of which are the nature of its microyielding and the nature of its fully reversible, hysteretic, stress-strain curves. In this article, we provide further evidence that Mg is a kinking nonlinear solid by showing excellent agreement between the predictions of our microscale model, in which fully reversible, dislocation-based incipient kink bands (IKBs) are the key microscale element, the experimental results obtained in our study, and, just as important, the results obtained by others. It follows that microyielding and the fully reversible hysteresis loops are most likely to be due to IKB formation, with the propensity for kinking being enhanced for coarse-grained samples up to a grain size of %50 lm, after which further increases in grain size have little effect. From the areas of the reversible loops, the critical resolved shear stresses (CRSSs) associated with the movement of basal plane dislocations are obtained and are shown to scale with the maximum flow stresses at which the loops are obtained. We also make the case that, at least for low strains, strains along the c-axis can be accommodated by invoking the formation of IKBs, mobile dislocation walls, and kink boundaries and should be included in future modeling of the deformation of polycrystalline Mg.

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Section: A Knementioning

confidence: 83%

Section: B Correlation Between Kinking Bending and Twinningmentioning

confidence: 99%

Kinking Nonlinear Elasticity and the Deformation of Magnesium

Zhou

Barsoum

2009

Metall Mater Trans A

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“…For example, the related polymer polyethylene is employed for neutron moderation at the LANSCE facility (for a discussion of the forms of polyethylene see [3]). Previous applications of SMARTS have been focused on metallic materials (see for example [4][5][6][7][8][9]). This is partially due to difficulties in interpreting diffraction patterns of amorphous materials [10], and partially because of the relatively few polymers that could be successfully probed in the bulk by diffraction methods.…”

Section: Introductionmentioning

confidence: 99%

“…Amorphous PTFE has the same repeat atomic structure as the crystalline domains but without significant order. The extreme molecular weight of PTFE (∼1×10 6 ), allows a given polymer chain to assemble in both amorphous and crystalline regions [18].…”

Section: Introductionmentioning

confidence: 99%

In-situ Measurement of Crystalline Lattice Strains in Polytetrafluoroethylene

et al. 2007

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Strain measurements by neutron diffraction are employed as an in situ technique to obtain insight into the deformation modes of crystalline domains in a deformed semi-crystalline polymer. The SMARTS (Spectrometer for MAterials Research at Temperature and Stress) diffractometer has been used to measure the crystalline lattice displacements in polytetrafluoroethylene (PTFE) for crystalline phase IV (at room temperature) in tension and compression and for crystalline phase I (at 60°C) in compression. The chemical structure of PTFE, -(C 2 F 4 )-n , makes it ideally suited for investigation by neutron methods as it is free of hydrogen that results in limited penetration depths and poor diffraction acquisition in most polymers. Deformation parallel to the prismatic plane normals is shown to occur by inter-polymer chain compression with a modulus ∼10× bulk, while deformation parallel to the basal plane normal occurs by intra-polymer chain compression with a modulus ∼1000× bulk, corresponding with theoretical values for a PTFE chain modulus. Deformation parallel to the pyramidal plane normals is accommodated by interpolymer chain shear.

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“…[1,2,[7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] These reports were generated using a combination of four processes: optical microscopy, transmission electron microscopy (TEM), neutron diffraction, and automated electron backscatter diffraction (ESBD). Optical microscopy can only identify probable twins using grain shape as the sole criteria.…”

Section: Introductionmentioning

confidence: 99%

A semiautomated electron backscatter diffraction technique for extracting reliable twin statistics

Henrie

Mason

Hansen

2004

Metall Mater Trans A

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A framework has been developed for extracting reliable twin statistics from a deformed microstructure using crystallographic twin identification techniques with spatially correlated electron backscatter diffraction (EBSD) data. The key features of this analysis are the use of the mathematical definition of twin relationships, the inclination of the common K 1 plane at a twin boundary, and the correct identification of the parent orientation in a parent/twin pair. Methods for identifying the parent in a parent/twin pair will be briefly discussed and compared. Twin area fractions are then categorized by operative twin systems, number of active twin variants in each system, and corrected twin widths. These statistics are reported here for ␣-zirconium samples deformed in quasi-static four-point bend beams and in a 100 m/s Taylor cylinder impact test. Analysis of the statistics also begins to reveal the roles that deformation rate and relative orientation of the boundary conditions to the material's symmetry axes play in determining the twinning activity that accommodates the imposed boundary conditions. These improved twin statistics can help quantify the deformation processes in materials that deform by twinning as well as serve to provide better validation of proposed models of the deformation processes.

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Uniaxial tensile deformation of uranium 6 wt pct niobium: A neutron diffraction study of deformation twinning

Cited by 58 publications

References 32 publications

Kinking Nonlinear Elasticity and the Deformation of Magnesium

Kinking Nonlinear Elasticity and the Deformation of Magnesium

In-situ Measurement of Crystalline Lattice Strains in Polytetrafluoroethylene

A semiautomated electron backscatter diffraction technique for extracting reliable twin statistics

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