The influence of tantalum on the high temperature characteristics of lamellar gamma + alpha 2 titanium aluminide

Vojtěch, Dalibor; Popela, T.; Hamáček, Jiří; Kutzendörfer, Jaroslav

doi:10.1016/j.msea.2011.07.070

Cited by 24 publications

(8 citation statements)

References 31 publications

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“…The lattice distortion of c/a increases and keeps stable with further addition. The atomic radius of Nb is bigger than that of Ti atom because of its high position in the periodic table, and presence of Nb atoms will replace the smaller Ti atoms in the TiAl lattice, thereby resulting in lattice distortion . With the increase of Nb, the lattice distortion of γ increases.…”

Section: Resultsmentioning

confidence: 99%

Effects of Nb on Microstructure and Mechanical Properties of Ti42Al2.6C Alloys

et al. 2018

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Ti42Al2.6C-xNb (x ¼ 0, 2, 4, 6, and 8 at%, similarly hereinafter) alloys are synthesized by melting to investigate the effects of Nb on microstructure and mechanical properties, especially the formation of B2 phase and high temperature tensile properties. The results show that lamellar colony size decreases from 33.3 to 13.2 mm and lamellar space decreases from 193.4 to 139.6 nm with increasing Nb from 0 to 8%. Lattice parameters of γ and α 2 phase change and B2 phase forms among lamellar colonies with the addition of Nb. The volume fraction of B2 phases and content of Nb in Ti 2 AlC phases increase with increasing Nb. B2 phases form between lamellar colonies because of Nb segregation. As high-melting-point element, Nb increases heterogenous nucleation particles and impedes grain growing. Compressive strength increases from 1568 to 1912 MPa with increasing Nb from 0 to 6% and then decreases at 8% Nb. Tensile strength at 750 C can reach 465 MPa and the strain is only 2.4% when the Nb content is 6%. The increased strength is resulted from refined microstructure and solid solution of Nb. And the decreased strength is because many B2 phases acts as crack source.

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Section: Resultsmentioning

confidence: 99%

Effects of Nb on Microstructure and Mechanical Properties of Ti42Al2.6C Alloys

et al. 2018

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“…The differences in microhardness are also caused by different alloying elements. Vojtěch et al [44] reported that Ta is more efficient solid solution strengthener than Nb which leads to higher microhardness of TiAl-based alloys modified with Ta when compared to that of Nb containing alloys. Table 7 summarises the results of room-temperature compression strength, 0.2 % offset yield strength and plastic deformation to fracture of the studied alloys.…”

Section: Microstructurementioning

confidence: 99%

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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“…Among various high-temperature materials, lightweight TiAl-based alloys are of great interest due to their low density and a good combination of mechanical properties at elevated temperatures [ 1 , 2 , 3 , 4 , 5 , 6 ]. These materials can fulfil requirements for some structural applications in the automotive, energy, and aerospace industries.…”

Section: Introductionmentioning

confidence: 99%

Processing and Microstructure of As-Cast Ti-45Al-2W-xC Alloys

Cegan,

Kamyshnykova,

Lapin

et al. 2022

Materials

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The metallurgical preparation and microstructure of as-cast Ti-45Al-2W-xC (in at.%) alloys were investigated. Five alloys with carbon content ranging from 0.38 to 1.96 at.% were prepared by vacuum induction melting (VIM) in graphite crucibles, followed by centrifugal casting into graphite moulds. A master 15W-85Al (at.%) alloy with a relatively low melting point and TiC powder were used to facilitate fast dissolution of W during VIM and to achieve the designed content of C in the as-cast alloys, respectively. The increase in the content of C affects the solidification path of the studied alloys. Differential thermal analysis (DTA) and microstructural observations show that the alloys with carbon content up to 0.75 at.% solidify with β primary phase and their dendritic as-cast microstructure consists of the α2(Ti3Al) + γ(TiAl) lamellar regions, retained B2 phase enriched by W and single γ phase formed in the interdendritic region. The increase in the content of C above 0.75 at.% leads to the formation of primary lathe-shaped Ti2AlC carbides, which act as effective heterogeneous nucleation sites of β dendrites during the solidification and grain refinement of the alloys with 1.15 and 1.96 at.% C. The increase in the content of C leads to an increase in Vickers hardness and elastic modulus in the alloys containing 1.96 at.% C.

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The influence of tantalum on the high temperature characteristics of lamellar gamma + alpha 2 titanium aluminide

Cited by 24 publications

References 31 publications

Effects of Nb on Microstructure and Mechanical Properties of Ti42Al2.6C Alloys

Effects of Nb on Microstructure and Mechanical Properties of Ti42Al2.6C Alloys

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

Processing and Microstructure of As-Cast Ti-45Al-2W-xC Alloys

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