Five-parameter intervariant boundary characterization of martensite in commercially pure titanium

Farabi, Ehsan; Hodgson, Peter; Rohrer, Gregory S.; Beladi, Hossein

doi:10.1016/j.actamat.2018.05.023

Cited by 94 publications

(43 citation statements)

References 52 publications

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“…Therefore, the closest variants common to both β grains are at 4.5 • from each other and a LAGB remained at the localization of the prior β GB. The presence of large clusters of colonies of similar orientation was already reported in the literature under different names: "double colonies" [20], "double Burgers boundary" [44], "feather microstructure" [45], or "plumes" [15,46].…”

Section: Analysis Of the Propension Of The α Feather-like Microstructmentioning

confidence: 65%

Analysis of Cold Dwell Fatigue Crack Initiation Site in a β-Forged Ti-6242 Disk in Relation with Local Texture

Germain

Samih

Delaleau

et al. 2020

Metals

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The α and prior β textures and microtextures of a lamellar Ti6242 forged disk were characterized by advanced electron back scattered diffraction (EBSD) and related to crystallographic features of faceted crack initiation sites of dwell fatigue specimens tested along the radial direction (RD). Large feather-like structures of α colonies with close orientations were observed at boundaries of elongated prior β grains. Their orientation belongs to the <11-20>α//z fiber, aligning the c-axis in RDs (z: axial direction of the disk). They are inherited from prior β grains belonging to the major <100>β and minor <111>β//z fibers. These feather-like structures are strong regions of the forging that act as a preferential crack initiation site. Adjacent to them, one can observe large colony with evidence of prismatic slip. Thus, the facet formation seems triggered by stress redistribution from “weak” to “strong” regions due to the elastic and plastic anisotropy. Finally, the occurrence of neighboring β grains able to share close oriented feather-like colonies is discussed considering the reconstructed β microtexture and texture. This study may be helpful for further texture control during the forging process.

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Section: Analysis Of the Propension Of The α Feather-like Microstructmentioning

confidence: 65%

Analysis of Cold Dwell Fatigue Crack Initiation Site in a β-Forged Ti-6242 Disk in Relation with Local Texture

Germain

Samih

Delaleau

et al. 2020

Metals

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show abstract

“…In the present study, one can expect that the β water cooling should be able to produce many new α orientations in both the Zr alloys, resulting in their grain orientations markedly different from those in the as-received specimens. In addition, the Burgers OR also predicts five possible misorientations between different α variants generated by the same β orientation, namely 10.5°/<0001>, 60°/<11-20>, 60.8°/<34-71>, 63.3°/<5 5 -10 3> and 90°/<34-70> (<34-71> and <34-70> are approximated integer indices of <1 1.38 −2.38 0.36> and <1 1.38 −2.38 0>, respectively, as reported in literature) [41]. Assuming no variant selection, the total frequency of the three misorientations around 60° can reach ~70% [42].…”

Section: Discussionmentioning

confidence: 99%

Comparative Study of Microstructural Characteristics and Hardness of β-Quenched Zr702 and Zr–2.5Nb Alloys

et al. 2019

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In this study, two commercial Zr alloys (Zr702 and Zr–2.5Nb) were subjected to the same β-quenching treatment (water cooling after annealing at 1000 °C for 10 min). Their microstructural characteristics and hardness before and after the heat treatment were well characterized and compared by electron channel contrast (ECC) imaging, electron backscatter diffraction (EBSD) techniques, and microhardness measurements. Results show that after the β quenching, prior equiaxed grains in Zr702 are transformed into Widmanstätten plate structures (the average width ~0.8 μm) with many fine precipitates distributed along their boundaries, while the initial dual-phase (α + β) microstructure in Zr–2.5Nb is fully replaced by fine twinned martensitic plates (the average width ~0.31 μm). Differences in alloying elements (especially Nb) between Zr702 and Zr–2.5Nb are demonstrated to play a key role in determining their phase transformation behaviors during the β quenching. Analyses on crystallographic orientations show that the Burgers orientation relationship is well obeyed in both the alloys with misorientation angles between α plates essentially focused on ~60°. After β quenching, the hardnesses of both alloys were increased by ~35%–40%. Quantitative analyses using the Hall–Petch equation suggest that such an increase was mainly attributable to phase transformation-induced grain refinements. Since Nb is able to effectively refine the β-quenched structures, a higher hardness increment is produced in Zr–2.5Nb than in Zr702.

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“…The orientations of the resulting HCP grains relative to the BCC parent grains are governed by the Burgers orientation relationship [11], which comprise 12 crystallographic α/α' variants. The relative fractions of these variants, which are determined by materials processing conditions, affect the overall texture of Ti alloys and therefore their mechanical properties [12,13]. A special type of HCP variant cluster arrangements can easily form to accommodate transformation strain [12,[14][15][16].…”

Section: Introductionmentioning

confidence: 99%

“…The relative fractions of these variants, which are determined by materials processing conditions, affect the overall texture of Ti alloys and therefore their mechanical properties [12,13]. A special type of HCP variant cluster arrangements can easily form to accommodate transformation strain [12,[14][15][16]. The boundaries between adjacent variants within each cluster are variant selection II (V2) boundaries [14] or 60°/ 1210 boundaries, i.e.…”

Section: Introductionmentioning

confidence: 99%

Introducing transformation twins in titanium alloys: an evolution of α-variants during additive manufacturing

Wang

Chao

Yang

et al. 2020

Materials Research Letters

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Five-parameter intervariant boundary characterization of martensite in commercially pure titanium

Cited by 94 publications

References 52 publications

Analysis of Cold Dwell Fatigue Crack Initiation Site in a β-Forged Ti-6242 Disk in Relation with Local Texture

Analysis of Cold Dwell Fatigue Crack Initiation Site in a β-Forged Ti-6242 Disk in Relation with Local Texture

Comparative Study of Microstructural Characteristics and Hardness of β-Quenched Zr702 and Zr–2.5Nb Alloys

Introducing transformation twins in titanium alloys: an evolution of α-variants during additive manufacturing

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