The deformation and fracture of TiAl at elevated temperatures

Lipsitt, H. A.; Shechtman, D.; Schafrik, Robert E.

doi:10.1007/bf03161822

Cited by 494 publications

(101 citation statements)

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“…(4) log(K' ac.o) =10g K + Iogfc.+ Iogfo -"""" (5) On the other hand, activity coefficient f is represented by Eqs. (6) and (7) Relation between calcium and oxygen contents in molten titanium aluminide in vacuum induction melting with a calcia crucible (Ti-37masso/o).…”

mentioning

confidence: 99%

Changes in Oxygen Contents of Titanium Aluminides by Vacuum Induction, Cold Crucible Induction and Electron Beam Melting.

et al. 1992

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mentioning

confidence: 99%

Changes in Oxygen Contents of Titanium Aluminides by Vacuum Induction, Cold Crucible Induction and Electron Beam Melting.

et al. 1992

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Section: Resultsmentioning

confidence: 73%

“…With this knowledge, the power-law behavior identified here is possibly explained by diffusional creep at low stresses with a change to dislocation creep at high stresses, both of which being controlled by diffusion via dislocation pipes. This hypothesis is supported by the observation of dislocation alignment and subgrain formation during the creep deformation of gamma alloys (19,20).An Arrhenius plot of the data, shown in Figure 3, indicates that the activation energy for steady-state creep deformation, Qact, is approximately 300 kJ/mole. While this value is in agreement with previous measurements (8-10), it is nearly double the measured activation energy for interdiffusion in single phase gamma titanium aluminide (21).…”

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confidence: 65%

Steady-state creep deformation of investment cast near-gamma titanium aluminide

Wheeler

London

Larsen

1992

Scripta Metallurgica et Materialia

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IntroductionThe ongoing search for increased aircraft engine performance has prompted the materials community to investigate intermetallic compounds as potential replacement materials for nickel-and cobalt-based superalloys. Of particular interest over the past decade has been near-gamma titanium aluminides due to their low density, high modulus and strength retention at elevated temperatures, and good environmental resistance (1,2).While many investigators have studied the microstructure/property relationships of gamma alloys, only a limited amount of work has been performed on their creep behavior (2-4). Since gamma titanium aluminides have been targeted for use at temperatures approaching 875°C, it is clearly important to understand their elevated temperature deformation characteristics.The vast majority of creep studies performed to date have concentrated on alloy systems prepared by wrought or powder metallurgy techniques (5-11).However, recent developments have identified investment casting as a viable method for producing complex, near-net shape gamma titanium aluminide components (12-15). As such, the need to examine the creep behavior of these alloys in the cast product form has prompted the current investigation. The stress dependency and activation energy for steady-state creep deformation were determined for cast, near-gamma alloy Ti-48AI-2Nb-2Cr (at.%). Post-test microscopy also was performed to characterize the microstructural evolution in these materials after prolonged high temperature exposure. The results are discussed with respect to potential creep deformation mechanisms operating within gamma titanium aluminides. Exoerimental ProcedureThe material for this study was produced by Vacuum Arc Remelting (VAR) and casting into 1.6 cm diameter x 15.2 cm test bars. Following casting, the material was hot isostatically pressed at 1260°C/172 MPa for 4 hours. The measured chemistry of the castings is given in Table I IntroductionThe ongoing search for increased aircraft engine performance has prompted the materials community to investigate intermetallic compounds as potential replacement materials for nicke1-and cobalt-based superalloys. Of particular interest over the past decade has been near-gamma titanium aluminides due to their low density, high modulus and strength retention at elevated temperatures, and good environmental resistance (l,2). While many investigators have studied the microstructure/property relationships of gamma alloys, only a limited amount of work has been performed on their creep behavior (2-4). Since gamma titanium aluminides have been targeted for use at temperatures approaching 875°C, it is clearly important to understand their elevated temperature deformation characteristics.The vast majority of creep studies performed to date have concentrated on alloy systems prepared by wrought or powder metallurgy techniques (5-1 I). However, recent developments have identified investment casting as a viable method for producing complex, near-net shape gamma titanium aluminide componen...

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“…Kawabata et al 1) reported that the ductility at room temperature improved with increasing purity. Lipsitt et al 2) investigated the DBTT of a Ti-40 mol%Al (abbreviated hereafter as Ti-40Al) alloy made fine-grained by extrusion. They reported that the specimen tensile-tested at 1073 K showed cleavage and intergranular fracture with some indications of ductility, and the DBTT of the Ti-Al alloy was about 1073 K. Hosomi and Maeda 3) investigated tensile properties of a Ti-48.5 mol%Al (Ti-48.5Al) alloy made finegrained by isothermal hot pressing.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties of Ultrahigh-Purity Ti-45 mol%Al Alloy

et al. 2002

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An ultrahigh-purity Ti-45 mol%Al alloy ingot was isothermally hot-pressed along each of the X, Y and Z coordinates at 1473 K. The hot-pressed ingot consisted mainly of very fine recrystallized grains, with an average size of 5 µm. The mechanical properties of this finegrained Ti-Al alloy were examined by tensile test at 293 K, 823 K, and 923 K at strain rate of 1.1 × 10 −4 s −1 in a vacuum of 1.3 × 10 −3 Pa. The ductile-brittle transition temperature (DBTT) was determined by the tensile tests and scanning electron microscope observation of the fracture surfaces of the samples. This ultrahigh-purity Ti-45 mol%Al alloy showed the following excellent high-temperature mechanical properties: (1) The 0.2% proof strength was 486 MPa and elongation at 923 K was 45%. (2) The DBTT was 870 K, which is about 200 K lower than that of conventional binary Ti-Al alloys with similar composition.

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The deformation and fracture of TiAl at elevated temperatures

Cited by 494 publications

References 2 publications

Changes in Oxygen Contents of Titanium Aluminides by Vacuum Induction, Cold Crucible Induction and Electron Beam Melting.

Changes in Oxygen Contents of Titanium Aluminides by Vacuum Induction, Cold Crucible Induction and Electron Beam Melting.

Steady-state creep deformation of investment cast near-gamma titanium aluminide

Mechanical Properties of Ultrahigh-Purity Ti-45 mol%Al Alloy

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