Microstructure, tensile, and creep behavior of O+BCC Ti2AlNb alloys processed using induction-float-zone melting

C. J. Boehlert, J. F. Bingert

Research output: Contribution to journalArticle

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Abstract

The microstructure, tensile, and tensile-creep behavior were studied for orthorhombic (O) plus body-centered cubic (BCC) Ti-22Al-24Nb and Ti-26Al-27Nb (at.%) alloys processed using induction-float-zone melting (IFZM). Microstructure studies were performed using scanning and transmission electron microscopy (SEM and TEM), automated electron back-scattered diffraction (EBSD), and X-ray diffraction (XRD). Upon solidification, the BCC phase evolved with [100] oriented nearly parallel to the longitudinal rod direction. During the slow cool through the O+BCC-phase field, O-variants formed in a fine lath network within the parent BCC. The as-processed Ti-26Al-27Nb rod was strongly textured with an approximately equal distribution of six resolvable O-variants. The retained BCC phase, which was sandwiched between O laths, maintained a higher volume fraction (Vf∼0.20) in Ti-22Al-24Nb compared to Ti-26Al-27Nb (Vf∼0.05). The tensile and creep behavior of the as-processed microstructures were evaluated with the tensile axis oriented parallel to the longitudinal rod direction. The fully lath O+BCC Ti-22Al-24Nb microstructure exhibited a room-temperature yield strength of 836 MPa and an elongation-to-failure of 4.5%. Surface slip traces revealed that slip was compatible between the O and BCC phases. An untransformed-BCC Ti-26Al-27Nb microstructure, oriented with [100] nearly parallel to the tensile axis, exhibited localized deformation bands resulting in an elongation of more than 5.9% and an average yield strength of 828 MPa. In terms of the creep behavior, the secondary creep rates revealed that the fully lath O+BCC Ti-26Al-27Nb microstructure significantly outperformed that for all other O-based alloys. For applied stresses greater than 300 MPa, an activation energy of 346 kJ/mol and a creep exponent of 5.1 were measured, while for lower applied stresses the creep exponent transitioned to a value of 2.3. Overall, this work shows that induction-float-zone processing produces textured fully lath O+BCC microstructures containing an attractive balance of room- and elevated-temperature properties for Al concentrations as high as 26 at.%. Crown

Original languageEnglish (US)
Pages (from-to)400-408
Number of pages9
JournalJournal of Materials Processing Technology
Volume117
Issue number3
DOIs
StatePublished - Nov 23 2001
Externally publishedYes

Profile

Microstructure
Creep
Acetanilides
Ileal Diseases
Learned Helplessness
Addison Disease
Yield stress
Transmission electron microscopy
Scanning electron microscopy
Zone melting
Elongation
Temperature
Edema Disease of Swine
African Swine Fever
Iduronidase
Fingersucking
Accessory Nerve
Carbamyl Phosphate
Topical Administration
Fetal Development

Keywords

  • Body-centered cubic
  • Creep
  • Induction-float-zone melting
  • Microtexture
  • Orientation relationship
  • Orthorhombic
  • Tension

ASJC Scopus subject areas

  • Materials Science(all)

Cite this

Microstructure, tensile, and creep behavior of O+BCC Ti2AlNb alloys processed using induction-float-zone melting. / Boehlert, C. J.; Bingert, J. F.

In: Journal of Materials Processing Technology, Vol. 117, No. 3, 23.11.2001, p. 400-408.

Research output: Contribution to journalArticle

Boehlert, C. J.; Bingert, J. F. / Microstructure, tensile, and creep behavior of O+BCC Ti2AlNb alloys processed using induction-float-zone melting.

In: Journal of Materials Processing Technology, Vol. 117, No. 3, 23.11.2001, p. 400-408.

Research output: Contribution to journalArticle

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title = "Microstructure, tensile, and creep behavior of O+BCC Ti2AlNb alloys processed using induction-float-zone melting",
abstract = "The microstructure, tensile, and tensile-creep behavior were studied for orthorhombic (O) plus body-centered cubic (BCC) Ti-22Al-24Nb and Ti-26Al-27Nb (at.%) alloys processed using induction-float-zone melting (IFZM). Microstructure studies were performed using scanning and transmission electron microscopy (SEM and TEM), automated electron back-scattered diffraction (EBSD), and X-ray diffraction (XRD). Upon solidification, the BCC phase evolved with [100] oriented nearly parallel to the longitudinal rod direction. During the slow cool through the O+BCC-phase field, O-variants formed in a fine lath network within the parent BCC. The as-processed Ti-26Al-27Nb rod was strongly textured with an approximately equal distribution of six resolvable O-variants. The retained BCC phase, which was sandwiched between O laths, maintained a higher volume fraction (Vf∼0.20) in Ti-22Al-24Nb compared to Ti-26Al-27Nb (Vf∼0.05). The tensile and creep behavior of the as-processed microstructures were evaluated with the tensile axis oriented parallel to the longitudinal rod direction. The fully lath O+BCC Ti-22Al-24Nb microstructure exhibited a room-temperature yield strength of 836 MPa and an elongation-to-failure of 4.5%. Surface slip traces revealed that slip was compatible between the O and BCC phases. An untransformed-BCC Ti-26Al-27Nb microstructure, oriented with [100] nearly parallel to the tensile axis, exhibited localized deformation bands resulting in an elongation of more than 5.9% and an average yield strength of 828 MPa. In terms of the creep behavior, the secondary creep rates revealed that the fully lath O+BCC Ti-26Al-27Nb microstructure significantly outperformed that for all other O-based alloys. For applied stresses greater than 300 MPa, an activation energy of 346 kJ/mol and a creep exponent of 5.1 were measured, while for lower applied stresses the creep exponent transitioned to a value of 2.3. Overall, this work shows that induction-float-zone processing produces textured fully lath O+BCC microstructures containing an attractive balance of room- and elevated-temperature properties for Al concentrations as high as 26 at.%. Crown",
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AU - Boehlert,C. J.

AU - Bingert,J. F.

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Y1 - 2001/11/23

N2 - The microstructure, tensile, and tensile-creep behavior were studied for orthorhombic (O) plus body-centered cubic (BCC) Ti-22Al-24Nb and Ti-26Al-27Nb (at.%) alloys processed using induction-float-zone melting (IFZM). Microstructure studies were performed using scanning and transmission electron microscopy (SEM and TEM), automated electron back-scattered diffraction (EBSD), and X-ray diffraction (XRD). Upon solidification, the BCC phase evolved with [100] oriented nearly parallel to the longitudinal rod direction. During the slow cool through the O+BCC-phase field, O-variants formed in a fine lath network within the parent BCC. The as-processed Ti-26Al-27Nb rod was strongly textured with an approximately equal distribution of six resolvable O-variants. The retained BCC phase, which was sandwiched between O laths, maintained a higher volume fraction (Vf∼0.20) in Ti-22Al-24Nb compared to Ti-26Al-27Nb (Vf∼0.05). The tensile and creep behavior of the as-processed microstructures were evaluated with the tensile axis oriented parallel to the longitudinal rod direction. The fully lath O+BCC Ti-22Al-24Nb microstructure exhibited a room-temperature yield strength of 836 MPa and an elongation-to-failure of 4.5%. Surface slip traces revealed that slip was compatible between the O and BCC phases. An untransformed-BCC Ti-26Al-27Nb microstructure, oriented with [100] nearly parallel to the tensile axis, exhibited localized deformation bands resulting in an elongation of more than 5.9% and an average yield strength of 828 MPa. In terms of the creep behavior, the secondary creep rates revealed that the fully lath O+BCC Ti-26Al-27Nb microstructure significantly outperformed that for all other O-based alloys. For applied stresses greater than 300 MPa, an activation energy of 346 kJ/mol and a creep exponent of 5.1 were measured, while for lower applied stresses the creep exponent transitioned to a value of 2.3. Overall, this work shows that induction-float-zone processing produces textured fully lath O+BCC microstructures containing an attractive balance of room- and elevated-temperature properties for Al concentrations as high as 26 at.%. Crown

AB - The microstructure, tensile, and tensile-creep behavior were studied for orthorhombic (O) plus body-centered cubic (BCC) Ti-22Al-24Nb and Ti-26Al-27Nb (at.%) alloys processed using induction-float-zone melting (IFZM). Microstructure studies were performed using scanning and transmission electron microscopy (SEM and TEM), automated electron back-scattered diffraction (EBSD), and X-ray diffraction (XRD). Upon solidification, the BCC phase evolved with [100] oriented nearly parallel to the longitudinal rod direction. During the slow cool through the O+BCC-phase field, O-variants formed in a fine lath network within the parent BCC. The as-processed Ti-26Al-27Nb rod was strongly textured with an approximately equal distribution of six resolvable O-variants. The retained BCC phase, which was sandwiched between O laths, maintained a higher volume fraction (Vf∼0.20) in Ti-22Al-24Nb compared to Ti-26Al-27Nb (Vf∼0.05). The tensile and creep behavior of the as-processed microstructures were evaluated with the tensile axis oriented parallel to the longitudinal rod direction. The fully lath O+BCC Ti-22Al-24Nb microstructure exhibited a room-temperature yield strength of 836 MPa and an elongation-to-failure of 4.5%. Surface slip traces revealed that slip was compatible between the O and BCC phases. An untransformed-BCC Ti-26Al-27Nb microstructure, oriented with [100] nearly parallel to the tensile axis, exhibited localized deformation bands resulting in an elongation of more than 5.9% and an average yield strength of 828 MPa. In terms of the creep behavior, the secondary creep rates revealed that the fully lath O+BCC Ti-26Al-27Nb microstructure significantly outperformed that for all other O-based alloys. For applied stresses greater than 300 MPa, an activation energy of 346 kJ/mol and a creep exponent of 5.1 were measured, while for lower applied stresses the creep exponent transitioned to a value of 2.3. Overall, this work shows that induction-float-zone processing produces textured fully lath O+BCC microstructures containing an attractive balance of room- and elevated-temperature properties for Al concentrations as high as 26 at.%. Crown

KW - Body-centered cubic

KW - Creep

KW - Induction-float-zone melting

KW - Microtexture

KW - Orientation relationship

KW - Orthorhombic

KW - Tension

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