A first report on the creep deformation and damage behavior of a fine grained fully transformed lamellar gamma TiAl alloy

Hayes, R.W.; McQuay, P.

doi:10.1016/0956-716x(94)90050-7

Cited by 48 publications

(16 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[32,33] In the late stages of tertiary creep, cavity growth is thought to Fig. 6-Dependence of the flow stresses r on the reciprocal activation volume 1/V determined at T = 1225 K for the alloys investigated.…”

Section: Resultsmentioning

confidence: 99%

Diffusion Bonding of γ(TiAl) Alloys: Influence of Composition, Microstructure, and Mechanical Properties

Herrmann

Appel

2009

Metall Mater Trans A

View full text Add to dashboard Cite

The metallurgical factors governing the solid-state diffusion bonding of TiAl alloys have been characterized using scanning electron microscopy together with energy-dispersive X-ray (EDX) spectroscopy and electron backscattered diffraction (EBSD) analysis. The investigations were performed on TiAl alloys with various compositions and microstructures, which had been thoroughly mechanically characterized. The process zone of the bonds typically consists of a fine-grained layer of a 2 (Ti 3 Al) phase at the former contact plane, followed by relatively large, defect-free c(TiAl) grains and a region of deformed parent material. The evolution of the process zone involves phase transformation and recrystallization processes, which are triggered by asperity deformation at the contact plane and the unavoidable contamination of the diffusion couple with oxygen and nitrogen. The structural details depend on the alloy composition and the bonding conditions. In the final section of the article, technical aspects, including the tensile strength of diffusion bonds, will be discussed.

show abstract

Section: Resultsmentioning

confidence: 99%

Diffusion Bonding of γ(TiAl) Alloys: Influence of Composition, Microstructure, and Mechanical Properties

Herrmann

Appel

2009

Metall Mater Trans A

View full text Add to dashboard Cite

show abstract

“…The first mechanism is based on the assumption that dislocation glide and climb is hindered by a reduced interface spacing. [33,34] The second mechanism proposes that the dislocation motion is restricted by the c/a 2 -interfaces causing a bowing out of dislocation segments between the interfaces. [19,35,36] TEM investigations on the creep tested Ti-46.5 at%Al-4 at.%(Cr,Nb,Ta,B) alloy samples confirmed the existence of both mechanisms.…”

Section: Reviewsmentioning

confidence: 99%

Mechanical Size‐Effects in Miniaturized and Bulk Materials

et al. 2006

View full text Add to dashboard Cite

Interfaces and surfaces can impose substantial mechanical size‐effects on materials. The deformation mechanisms become increasingly constrained when microstructural and/or geometrical dimensions decrease. This effect can improve, for example, the creep resistance of a bulk lamellar material, but it may cause failure for a miniaturized material component due to high internal stresses. Several dislocation mechanisms causing size‐dependent flow stresses for (sub)micron‐sized metals and metallic thin films are addressed in this paper and the current understanding of size‐effects in miniaturized and bulk materials is reviewed. The beneficial application of mechanical size‐effects is demonstrated for TiAl alloys and nanostructured hard coatings.

show abstract

“…[3][4][5][6][7][8] The increase in creep resistance of fully lamellar microstructures is generally attributed to the a 2 laths and g͞g interfaces acting as barriers to slip. 4,9 On the other hand, it has been suggested that the decreased creep resistance of the duplex microstructure compared to that of the equiaxed g microstructure is a result of the increased glide mobility of 1͞2 ͗110͘ dislocations within the g matrix 10 of the former. Although it is generally accepted that the alloys exhibit power law creep behavior, the values of the stress exponent, n, appear to increase with increasing applied stress.…”

Section: Introductionmentioning

confidence: 99%

“…Although it is generally accepted that the alloys exhibit power law creep behavior, the values of the stress exponent, n, appear to increase with increasing applied stress. 9,11 This has been interpreted as being due to a transition from diffusional creep at low stresses to dislocation glide creep at high stresses. 5,[12][13][14] Although mechanical twinning during creep deformation of TiAl alloys has been extensively reported, 5,[15][16][17] its contribution to the creep process is not easily interpreted since traditional creep theories do not include such contributions.…”

Section: Introductionmentioning

confidence: 99%

Quantitative analysis of microstructures produced by creep of Ti–48Al–2Cr–2Nb–1B: Thermal and athermal mechanisms

Morris

Leboeuf

1998

J. Mater. Res.

View full text Add to dashboard Cite

A g-based TiAl alloy with equiaxed microstructure and fine grain size has been studied to analyze the deformation mechanisms responsible for the creep behavior. The microstructures produced by creep and high temperature deformation have been examined by TEM to obtain information about the different aspects characterizing the primary and secondary stages of creep. Mechanical twinning has been confirmed to occur in a fraction of the grains that never exceeds 50% while 1͞2 ͗110͘ dislocations are active within all the g grains. The twins are only responsible for a small amount of strain, but they lead to a subdivision of the microstructure and determine (directly or indirectly) the hardening process observed during the primary stage of creep. We have proposed that during the secondary stage the creep rate is determined by the unblocking of pinned dislocations by processes such as a pipe diffusion or cross slip that allow thermally activated glide of 1͞2 ͗110͘ dislocations on (001) planes.

show abstract

A first report on the creep deformation and damage behavior of a fine grained fully transformed lamellar gamma TiAl alloy

Cited by 48 publications

References 7 publications

Diffusion Bonding of γ(TiAl) Alloys: Influence of Composition, Microstructure, and Mechanical Properties

Diffusion Bonding of γ(TiAl) Alloys: Influence of Composition, Microstructure, and Mechanical Properties

Mechanical Size‐Effects in Miniaturized and Bulk Materials

Quantitative analysis of microstructures produced by creep of Ti–48Al–2Cr–2Nb–1B: Thermal and athermal mechanisms

Contact Info

Product

Resources

About