Variant selection by dislocations during α precipitation in α/β titanium alloys

Qiu, Derong; Shi, Rongpei; Zhang, D.; Lu, Wenbo; Wang, Y.

doi:10.1016/j.actamat.2014.12.044

Cited by 139 publications

(45 citation statements)

References 52 publications

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“…This approach predisposes the nucleation of a select number of precipitate variants that are commensurate with the crystallography of deformation features, e.g. 110 and 112 , and 1120 directions in fcc and hcp, respectively [9][10][11]; meaning potentially fewer precipitate variants form compared to the undeformed condition [9,11]. However, low stacking fault energy fcc-based CCAs, like Al x -Co-Cr-Fe-Ni (x = 0-0.3), are highly susceptible to {111} 112 twining on multiple {111} planes [12,13].…”

Section: Main Textmentioning

confidence: 99%

Crystallographically degenerate B2 precipitation in a plastically deformed fcc-based complex concentrated alloy

Choudhuri

Shukla

Green

et al. 2018

Materials Research Letters

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Section: Main Textmentioning

confidence: 99%

Crystallographically degenerate B2 precipitation in a plastically deformed fcc-based complex concentrated alloy

Choudhuri

Shukla

Green

et al. 2018

Materials Research Letters

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“…In this regard, it is worth noting that the heterogeneous nucleation on lattice defects, such as dislocations, twins or grain boundaries in matrix phases during diffusional phase transformation and precipitation reactions, would affect the variant selection, but not the specific orientation relationship (e.g. Furuhara & Maki, ; Qiu, Shi, Zhang, Lu, & Wang, ). For heterogeneous nucleation on dislocations, effective accommodation of the transformation strain by the strain field of dislocation occurs, thereby leading to the precipitate variant(s) with the direction of the maximum misfit nearly parallel to the dislocation Burgers vector (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…For heterogeneous nucleation on dislocations, effective accommodation of the transformation strain by the strain field of dislocation occurs, thereby leading to the precipitate variant(s) with the direction of the maximum misfit nearly parallel to the dislocation Burgers vector (e.g. Furuhara & Maki, ; Qiu et al, ). Assuming the energetically most favoured COR‐2 rutile precipitated on the [11

\bar{1}

] grt ‐oriented screw dislocations with 1/2 [11

\bar{1}

] grt Burgers vector, the rutile nucleus would have its largest misfit direction [3

\bar{1}

5] rt //[11

\bar{1}

] grt (4.0% misfit) parallel to the Burgers vector to accommodate the transformation strain, and have its smallest misfit direction parallel to the other three <103> rt //<111> grt directions (0.3% misfit) for the preferential development of three variants of rutile needle crystals at 70.5° inclination angle with respect to the dislocation lines (see Figure d for the stereogram and table 3 for the misfit data in Hwang et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…For heterogeneous nucleation on dislocations, effective accommodation of the transformation strain by the strain field of dislocation occurs, thereby leading to the precipitate variant(s) with the direction of the maximum misfit nearly parallel to the dislocation Burgers vector (e.g. Furuhara & Maki, 2001;Qiu et al, 2015). Figure 3d for the stereogram and table 3 for the misfit data in Hwang et al, 2016).…”

Section: Energetics Considerations For 'Solidstate Exsolution' Of Rmentioning

confidence: 99%

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Rutile inclusions in garnet from a dissolution‐reprecipitation mechanism

Hwang

Shen

Chu

et al. 2019

Journal Metamorphic Geology

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Metamorphic garnet commonly contains needle‐like rutile inclusions as well as equant rutile inclusions that surround quartz inclusions and range in size from submicrometer to nanometer. Although the origin of these equant rutile inclusions, that is, exsolution or non‐exsolution, has important implications for petrological and tectonic processes, the crystallographic characteristics of these inclusions have rarely been studied because of the small sizes and analytical difficulties involved. Here, we report the crystallographic characteristics pertinent to the genetic origin of minute equant rutile inclusions in cloudy, nearly spherically shaped garnet domains with Ti‐depleted compositions surrounding quartz inclusions in ultrahigh‐pressure garnet from several diamondiferous Erzgebirge quartzofeldspathic gneissic rock samples. TEM analyses show that the equant rutile crystals in cloudy garnet domains are partially bounded by the low‐energy {100}rt ± {110}rt ± {101}rt facets and have rather random crystallographic orientation relationships (CORs) with the garnet host, with preferential alignment of low‐energy lattice planes, for example, {100}rt//{112}grt, for some rutile crystals. Although the rather random CORs are unlikely to be attributed to solid‐state exsolution subjected to the stringent topotactic garnet lattice constraints, the characteristic subhedral {100}rt ± {110}rt ± {101}rt crystal forms of rutile can be rationalized by a metasomatic dissolution‐reprecipitation mechanism via a fluid phase. In this scenario, the quartz+fluid inclusions in garnet were first subjected to decompression microcracking during rock exhumation, followed by dissolution of Ti‐bearing garnet matrix at the crack tips or along the crack surfaces and subsequent reprecipitation of rutile, apatite, gahnite, akdalaite, and Ti‐depleted garnet. The rapid coalescence between rutile and garnet crystals in fluid or direct attachment of rutile crystals onto the dissolving crack surfaces would then yield the rather random CORs as reported here. These results, along with previous work on rutile needles, indicate rather diverse genesis of rutile inclusions in various crystal forms, thus shedding light on the controversial exsolution origin for other inclusion suite/microstructure in minerals.

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“…Moreover, defects such as dislocations generated during TMP in either b or a + b phase region act frequently as preferred nucleation sites for specific subsets of a variants [17][18][19][20][21]. Furthermore, the lattice distortion introduced within the b matrix by the precipitation of a phase introduces large local stress concentrations or "backstresses" which can influence VS within a local neighborhood [22][23][24].…”

Section: Introductionmentioning

confidence: 99%