Nucleation and growth of twins in Zr: A statistical study

Capolungo, Laurent; Marshall, P.; McCabe, Rodney J.; Beyerlein, Irene J.; Tomé, Carlos N.

doi:10.1016/j.actamat.2009.08.030

Cited by 268 publications

(170 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.…”

mentioning

confidence: 99%

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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mentioning

confidence: 99%

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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“…Regarding drivers for early twin formation, the 3D nature of the analysis has revealed the importance of grain size for early twin formation, figure 3. While positive grain size dependency of twinning has been reported previously for Mg [21], Ti [22] and Zr [7], the present 3D analysis provides a very clear picture of the size dependency because it does not suffer from intrinsic broadening of the distribution as a result of a 2D analysis. It has been suggested previously that the root cause for less twin formation in the case of small grains is related to the twin boundary energy cost being relatively high compared to the plastic work induced by the twin [23].…”

Section: Discussionmentioning

confidence: 65%

“…This consideration assumes the importance of grain boundaries on twin nucleation. The true twin thickness has been found to be independent of grain size in magnesium and zirconium by Tome' and colleagues [7,25] but strongly dependent on the grain size in titanium [26]. Nevertheless, they found that the number of twins, in grains that did twin, increased with increasing grain size.…”

Section: Discussionmentioning

confidence: 81%

“…in the absence of easy slip including a <c> component, twinning is commonly observed in Ti and other metals with an hcp crystal structure. This is particularly the case during compression loading [7]. In α titanium, four different twinning modes have been reported [8].…”

Section: Introductionmentioning

confidence: 99%

“…At room temperature, the predominant twinning mode is the {10-12}<-1011> tensile twin [9,10] , which corresponds to a rotation of 85° around the <11-20> axis. In some cases, this twin mode has been observed to result in almost complete grain reorientation after only modest levels of strain [7,9,11].…”

Section: Introductionmentioning

confidence: 99%

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Proceedings of the 13th World Conference on Titanium

2016

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Twin formation in alpha-Ti is a topic of much debate as the role of microstructure features and alloy chemistry on twin formation remains unclear. In the present work, early stage of twin formation, i.e. after 1% plastic compression, has been studied in 3D using diffraction contrast tomography. This technique has enabled to study a volume about 400 grains enabling statistical analysis. The family of twinned grains was compared with similarly orientated grains that had not twinned in respect of their neighbourhood and grain size. While the initial neighbourhood analysis did not identify any significant differences, 3D grain size analysis highlighted that grain size plays an important role during the early stage of twinning. Further, twin clusters/chains were identified, which form slightly imperfect 3D networks. A more detailed neighbourhood analysis of the parent grains associated with the twin clusters/chains demonstrate that strain localization in neighbouring grains well aligned for prismatic slip transfer promote the observed twin clustering.

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