Shock-induced deformation twinning and omega transformation in tantalum and tantalum–tungsten alloys

Hsiung, L.M.; Lassila, D.H.

doi:10.1016/s1359-6454(00)00287-1

Cited by 184 publications

(123 citation statements)

References 19 publications

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“…In this study, two kinds of ω phase were noticed: (1) nanosized spherical or ellipsoidal particles (ω ath ) (Figure 5d) that have been observed to occur on accelerated cooling in metastable-β titanium alloys [18,20,38] and (2) lamellae ω (stress-induced ω) (Figure 5c) which has been reported in titanium alloys after plastic deformation [23,44,45]. Shuffle of atoms in {112} β planes in the direction of 111 has been suggested as the formation mechanism for both ω types [44].…”

Section: Discussionsupporting

confidence: 51%

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Formation of Deformation-Induced Products in a Metastable-β Titanium Alloy during High Temperature Compression

Samiee

Casillas

Ahmed

et al. 2018

Metals

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A metastable-β titanium alloy, Ti-10V-3Fe-3Al (wt. %), was subjected to thermo-mechanical processing including the compression test at 725 • C, which is below the β transus temperature (780 • C), and at strain rate of 10 −3 s −1 . The presence of phases was determined using transmission electron microscopy and X-ray diffraction. Although the dynamic recovery took place together with slip, both deformation-induced α" martensite and ω were detected as other operating mechanisms for the first time in metastable-β titanium alloy deformed in α + β region. The volume fraction of stress-induced α" was higher than that of the same alloy deformed at room temperature due to a higher strain applied. Stress-induced twinning was not operational, which could be related to the priority of slip mechanism at high temperature resulted from thermally-assisted nucleation and lateral migration of kink-pairs.

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Section: Discussionsupporting

confidence: 51%

“…Shuffle of atoms in {112} β planes in the direction of 111 has been suggested as the formation mechanism for both ω types [44]. However, Hsiung et al [45] reported the glide of partial dislocations of 1/3 111 , 1/6 111 and 1/12 111 , which are formed from 1/2 111 perfect dislocation, as the formation mechanism of stress-induced ω.…”

Section: Discussionmentioning

confidence: 99%

Formation of Deformation-Induced Products in a Metastable-β Titanium Alloy during High Temperature Compression

Samiee

Casillas

Ahmed

et al. 2018

Metals

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“…In terms of validation, there is ample experimental evidence of twinning in shocked Ta [44][45][46][47][48], and under other loading conditions [49,50]. These works demonstrate, first, that twinning is normally initiated at material inhomogeneities, and, second, that twinning is generally accompanied by a significant amount of dislocation activity.…”

Section: Discussionmentioning

confidence: 99%

A Quasicontinuum study of nanovoid collapse under uniaxial loading in Ta

2008

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We analyze the mechanisms underlying the deformation of nanovoids in Ta single crystals subjected to cyclic uniaxial deformation using numerical simulations. Boundary and cell-size effects have been mitigated by means of the Quasicontinuum (QC) method. We have considered ∼1 billion-atom systems containing 11.2-nm voids. Two kinds of simulations have been performed, each characterized by a different boundary condition. First, we compress the material along the nominal [001] direction, resulting in a highly-symmetric configuration that results in high stresses. Second, we load the material along the high-index [4 8 19] direction to confine plasticity to a single slip system and break the symmetry. We find that the plastic response under these two conditions is strikingly different, the former governed by dislocation loop emission and dipole formation, while the latter is dominated by twinning. We calculate the irreversible plastic work budget derived from a loading-unloading cycle and identify the most relevant yield points. These calculations represent the first fully 3D, fully non-local simulations of any bcc metal using QC.

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“…Lots of other structural changes can occur during the plastic deformation of metals, such as twinning [26] [27] [28], phase transformation [29] [30] and fracture [31]. Mechanical twinning has mainly two e↵ects on plastic deformation: (1) It can subdivide the grains, acting as a barrier for dislocation slip, and therefore increase the work hardening rate.…”

Section: Micromechanics Of Shock Compression Of Solidsmentioning

confidence: 99%

“…The residual dislocation substructure after shock loading is summarised in Table 2.2. The dislocation structure 16: TEM dislocation micrographs of (a) 35 GP a laser shocked tantalum single crystal [28]; (b) 15 GP a plate impacted tantalum [29]; (c) 45 GP a plate impacted tantalum single crystal [29]; (d) 7 GP a plate impacted tantalum [36]; (e) 45 GP a plate impacted tantalum [29]; (f) 20 GP a plate impacted tantalum [36] …”

Section: Dislocations and Hardeningmentioning

confidence: 99%