Microstructure and Properties of Cast Ti‐46Al‐8Ta Alloy

Lapin, J.; Gabalcová, Zuzana; Bajana, Oto; Pelachová, T.; Staneková, Hana; Frkanova, K.

doi:10.1002/9781118998489.ch25

Cited by 3 publications

(5 citation statements)

References 20 publications

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“…In spite of the different chemical composition of the studied alloy, the yield strength R p 0.2 increases linearly with increasing Vickers microhardness HV m . Such linear dependence of the yield strength on the Vickers microhardness is in a good agreement with the results reported previously by Lapin et al [46][47][48] for Ti-46Al-2W-0.5Si, Ti-46Al-8Nb (at.%) and Ti-44Al-4Nb-4Zr-0.2Si-0.3B (at.%) alloys. Linear regression analysis of the experimental data shown in …”

Section: Microstructuresupporting

confidence: 92%

Preparation of TiAl-based alloys by induction melting in graphite crucibles

Čegan¹,

Szurman²,

Kursa³

et al. 2016

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Three TiAl-based alloys with nominal composition Ti-47Al-8Nb, Ti-47Al-8Ta and Ti-47Al--8Ta-0.3Y (at.%) were prepared by induction melting in graphite crucibles and centrifugal casting into graphite moulds. Chemical composition, microstructure and mechanical properties of the as-cast alloys are characterised. The melting in the graphite crucible leads to an increase of carbon content from 460 to 1020 wtppm and formation of fine carbide particles predominantly in the γ(TiAl) phase. Beside fine carbides, the addition of 0.3 at.% of yttrium results in formation of fine Y2O3 and YAl2 particles. The oxygen content depends on the chemical composition and varies between 330 and 780 wtppm for Ta and Nb containing alloys, respectively. The as-cast alloys exhibit relatively high values of room-temperature compression yield strength up to 922 MPa, ultimate compression strength up to 1793 MPa and plastic deformation to fracture up to 24.3 %. The compression yield strength increases linearly with increasing Vickers microhardness of the as-cast alloys. From the point of view of chemical composition, microstructure and studied mechanical properties, induction melting in the graphite crucible and centrifugal casting into graphite mould can be considered as a suitable method of preparation of TiAl-based alloys.K e y w o r d s :

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Section: Microstructuresupporting

confidence: 92%

Preparation of TiAl-based alloys by induction melting in graphite crucibles

Čegan¹,

Szurman²,

Kursa³

et al. 2016

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“…The Ni-Al-based intermetallics (modified, e.g., by Ta, Mo [22], by Ti, Fe [23], by Mo, Cr, V [24], etc.) are important for technical applications and hence, it is advisable to know the interdiffusion coefficients.…”

Section: Evaluation Of Diffusion Coefficientsmentioning

confidence: 99%

Calculation of ternary interdiffusion coefficients using a single diffusion couple

Čermák¹,

Rothová²

2016

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In this paper, the simple numerical algorithm is proposed that enables to estimate ternary interdiffusion coefficients D in systems with not too strongly interacting components. D's are obtained from measurement with a single model diffusion couple. They can be used to predict concentration curves Ci(x) (i = 1, 2, 3) in arbitrary time with numerical errors that are comparable with experimental errors of measurement of ci itself and comply with theoretical constraints following from the linear irreversible thermodynamics. The algorithm does not need any external thermodynamic data and external measurements (e.g., it is not necessary to measure the shift of inert markers in the interface). It can be applied using commonly accessible SW, and it is not time-consuming. Values of D are close to those obtained with the help of much more laborious experimental -also approximate -methods.K e y w o r d s : diffusion, interdiffusion, ternary alloys, transport properties, ternary diffusion coefficients

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“…On the other hand, the FL/NL alloys exhibit better creep resistance, higher fracture toughness and crack propagation resistance than DP/NG structures [8,9]. However, a coarse-grained lamellar structure results in low RT tensile strength and ductility [7,10]. The yield strength and ductility of TiAl-based alloys can be significantly increased by decreasing grain size [11].…”

Section: Introductionmentioning

confidence: 99%

“…Basically, two main approaches have been investigated to refine the coarse-grained structure of ascast TiAl-based alloys: (i) solid-state phase transformations and (ii) alloying with minor additions. Numerous research works have been published on grain refinement based on solid-state phase transformations and particularly on non-equilibrium phase transformations [15][16][17][18][19][20][21][22][23]. Indeed, a large range of microstructures can be obtained by varying the cooling rate from the α (Ti-based solid solution with A3 crystal structure) phase field ranging from the equilibrium lamellar structure to the Widmanstätten structure, feath- ery structure, massive structure and finally the highly metastable retained α structure.…”

Section: Introductionmentioning

confidence: 99%

“…The alloying elements showing low diffusivity in both TiAl and Ti 3 Al phases decrease critical cooling rates required for the formation of massive γ M [19]. Some TiAl-based alloys have been specifically designed, as the "air hardenable" requiring only air cooling from the single α phase field to be fully transformed to massive γ M [10,[27][28][29][30][31]. However, many TiAl-based alloys do not exhibit massive transformation or this transformation is shifted to very high cooling rates.…”

Section: Introductionmentioning

confidence: 99%

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Grain refinement of cast peritectic TiAl-based alloy by solid-state phase transformations

Kamyshnykova¹,

Lapin²

2018

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The effect of solid-state phase transformations on grain refinement of cast peritectic TiAl-based alloy with nominal composition Ti-47Al-5Nb-0.2B-0.2C (at.%) has been investigated. Three multi-stage heat treatment routes consisting of pretreatment in single α phase field followed by air, oil or water cooling and subsequent annealing in α + γ or single α fields were applied to refine grain structure of the alloy. The microstructure of the as-cast samples consists of coarse fully lamellar α2(Ti3Al) + γ(TiAl) grains with a grain size of 1310 µm. The annealing of the pretreated samples consisting of massive γM and fine lamellar α2 + γ grains in the α + γ phase field leads to the formation of a duplex type of microstructure composed of lamellar α2 + γ and single γ phase grains with a grain size ranging from 14 to 22 µm. The solution annealing in the single α phase field of the pretreated samples aged in the α + γ phase field leads to the formation of fully lamellar α2 + γ grains with a grain size ranging from 395 to 472 µm.

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Microstructure and Properties of Cast Ti‐46Al‐8Ta Alloy

Cited by 3 publications

References 20 publications

Preparation of TiAl-based alloys by induction melting in graphite crucibles

Preparation of TiAl-based alloys by induction melting in graphite crucibles

Calculation of ternary interdiffusion coefficients using a single diffusion couple

Grain refinement of cast peritectic TiAl-based alloy by solid-state phase transformations

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