Origin of dislocations within tensile and compressive twins in pure textured Zr

Bhattacharyya, Dhriti; Cerreta, Ellen K; McCabe, Rodney J.; Niewczas, M.; Gray, George T.; Misra, Amit; Tomé, Carlos N.

doi:10.1016/j.actamat.2008.09.014

Cited by 54 publications

(27 citation statements)

References 23 publications

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“…The large shear of T2 twins makes them potential damage nucleation sites in the material. Though T2 twins are less frequent than T1 twins, they have also been observed in Co, [17] Zr, [27,37,38] Ti, [26,29] and an Mg-based alloy. [39] Reed-Hill et al observed kink bands (both inside the twin and outside the twin) adjacent to the tip of some T2 twins in Zr.…”

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“…At room temperature, T1 twinning is the most commonly observed twinning mode in Ti and other hexagonal metals with c/a ratio less than ffiffiffiffiffiffiffi ffi 8=3 p , such as Mg and Zr. [23][24][25][26][27][28][29] Several atomistic and grain-scale models have been proposed to account for the nucleation and growth of T1 twins. [30][31][32][33][34][35][36] In contrast, other twinning modes have received much less attention.…”

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Study of $$ \{ 11\bar{2} 1\} $$ Twinning in α-Ti by EBSD and Laue Microdiffraction

Wang

Barabash

Bieler

et al. 2013

Metall Mater Trans A

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Activity of the f11 " 21gh " 1 " 126i extension twinning (T2) mode was analyzed in a commercial purity Ti sample after 2 pct tensile strain imposed by four-point bending. The sample had a moderate c-axis fiber texture parallel to the tensile axis. Compared with the many f10 " 12gh " 1011i extension (T1) twins that formed in 6 pct of the grains, T2 twins were identified in 0.25 pct of the grains by scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD) maps. Most of the T2 twins exhibited irregular twin boundaries (TBs) on one side of the twin. Highresolution EBSD revealed both intermediate orientations at some matrix/twin interfaces and substantial lattice rotation within some T2 twins. Interactions between matrix hc + ai dislocations 1 3 h1 " 213i and a f11 " 21g T2 twin were investigated by combining SEM/EBSD slip trace characterization and Laue microdiffraction peak streak analysis. hc + ai dislocations that originally glided on a pyramidal plane in the matrix were found on other planes in both the matrix and the twin, which was attributed to extensive cross-slip of the screw component, whose Burgers vector was parallel to the twinning plane. On the other hand, thickening of the twin could engulf some pile-up edge components in front of the TB. During this process, these hc + ai dislocations transmuted from a pyramidal plane ð0 " 111Þ in the matrix to a prismatic plane ð " 1010Þ T in the twin lattice. Finally, possible mechanisms for the nucleation and growth of T2 twins will be discussed.

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Study of $$ \{ 11\bar{2} 1\} $$ Twinning in α-Ti by EBSD and Laue Microdiffraction

Wang

Barabash

Bieler

et al. 2013

Metall Mater Trans A

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“…It is well known that a ''tensile'' twin in hcp material like Zr can be formed by an effective rotation about [11.0] axis by $ 941 [33]. This is equivalent to an angle of 2j ¼ $861 between K1 ¼{10.2} and K2 ¼{ À10.2} [34].…”

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confidence: 99%

Load partitioning and evidence of deformation twinning in dual-phase fine-grained Zr–2.5%Nb alloy

Muránsky¹,

Daymond²,

Bhattacharyya³

et al. 2013

Materials Science and Engineering: A

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. a b s t r a c tIn situ neutron diffraction loading experiments were carried out on a cold-rolled dual-phase (a-phase, $ 10% b-phase) Zr-2.5%Nb alloy at room temperature. The specimens were cut at different angles from the rolling direction (RD) towards the transverse direction (TD), thus the loading axis changes gradually from the rolling to transverse direction. Due to the strong texture of the studied alloy, and unidirectional nature of deformation twinning, the changing loading direction with respect to initial texture has a significant impact on the collaborative slip-twinning deformation mode in the hexagonal close-packed (hcp) a-phase. The present neutron diffraction results provide direct evidence of {1 À 1.2}/1 À 1. À 1S ''tensile'' twins in the a-phase of dual-phase Zr-2.5%Nb alloy at room temperature.Additionally, TEM analysis was employed to confirm the presence of ''tensile'' twins, and determine if other type of twins were present. It is further clear from the neutron diffraction results that applied load is gradually transferred from the plastically softer a-phase to the plastically harder b-phase which acts as a reinforcing phase having a yield strength in the range 750-900 MPa depending on the loading direction.

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“…Dislocations and twins play an important role in the plastic deformation and hardening of Zr. The main twinning systems observed in zirconium are tensile twins in the {10 1 2}<10 1 1 > system and compressive twins in the {11 2 2}<11 2 3 > system [28]. Tensile twinning accommodates the elongation along the c-axis of the crystal, whereas compressive twinning accommodates the c-axis contraction [29].…”

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confidence: 99%

Microstructure and texture evolution in commercial-purity Zr 702 during cold rolling and annealing

Tan

et al. 2014

Int J Miner Metall Mater

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Microstructure and texture evolution in commercial-purity Zr 702 during cold rolling and annealing was investigated by optical microscopy, transmission electron microscopy, and X-ray diffraction. The results showed that crystallographic slip was the predominant deformation mechanism in the early stage of deformation. Deformation twins started to form when the rolling reduction was larger than 38.9%; both the dislocation density and the number of twins increased with increasing rolling reduction. The initial texture of the Zr 702 plate consisted of the basal fiber component. During cold rolling the strength of the basal fiber first decreased and then increased with increasing rolling reduction. The cold-rolled sheets were fully recrystallized after being annealed at 550°C. The recrystallization temperature and the size of recrystallized grains decreased with increasing rolling reduction. A larger rolling reduction resulted in a higher grain growth rate when the annealing temperature increased from 550°C to 700°C. The recrystallization texture was characterized by a major basal fiber and a minor {01 1 3}<2 1 1 0> component. The strength of the recrystallization texture increased with increasing rolling reduction.

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Origin of dislocations within tensile and compressive twins in pure textured Zr

Cited by 54 publications

References 23 publications

Study of $$ \{ 11\bar{2} 1\} $$ Twinning in α-Ti by EBSD and Laue Microdiffraction

Study of $$ \{ 11\bar{2} 1\} $$ Twinning in α-Ti by EBSD and Laue Microdiffraction

Load partitioning and evidence of deformation twinning in dual-phase fine-grained Zr–2.5%Nb alloy

Microstructure and texture evolution in commercial-purity Zr 702 during cold rolling and annealing

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