As-cast titanium aluminides microstructure modification

Duarte, Antônio Ricardo Calazans; Viana, Filomena; Santos, Henrique

doi:10.1590/s1516-14391999000300013

Cited by 18 publications

(5 citation statements)

References 9 publications

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“…At present there are three main approaches to component production: (i) extrusion and forging [21,22], (ii) casting [11,23,24] and (iii) powder technology [18,25e29]. As regards powder metallurgy, some preliminary papers about the use of EBM for the production of g-TiAl specimens can be found in literature.…”

Section: Introductionmentioning

confidence: 99%

Electron beam melting of Ti–48Al–2Cr–2Nb alloy: Microstructure and mechanical properties investigation

Biamino

Penna

Ackelid³

et al. 2011

Intermetallics

390

166

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Section: Introductionmentioning

confidence: 99%

Electron beam melting of Ti–48Al–2Cr–2Nb alloy: Microstructure and mechanical properties investigation

Biamino

Penna

Ackelid³

et al. 2011

Intermetallics

390

166

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“…In previous work with Ti-47Al and Ti-50Al alloys, heat treating at the same temperatures resulted in similar observations. However, for the Ti-47Al alloy, after 1h at 1400ºC (in the α field) the alloy exhibited a fully lamellar structure [9]. The present results indicate that all the treatments were performed in the α+γ field for Alloy 1, even at 1400ºC.…”

Section: Alloymentioning

confidence: 52%

“…Alloy 2 has an Al content of 46-47 at. % and so a fully lamellar structure was expected after heat treatment at 1400ºC [9]. The presence of γ-phase indicates that for this alloy 1400ºC is still in the α+γ field.…”

Section: Alloymentioning

confidence: 82%

Zr Bearing γ-TiAl Induction Melted

Barbosa

Duarte²,

Ribeiro³

et al. 2000

KEM

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This paper describes the processing results of TiAl alloys melted under argon atmosphere by induction melting, using crucibles made of calcia and stabilized zirconia. Castings were allowed to solidify inside the crucible, in order to simulate the worst situation using this processing. Segregation profiles of residual elements and microhardness of different phases were evaluated, as well as its relation with the "alpha-case" extension.Two TiAl alloys, with 1 at. % zirconium and zirconium free, were produced and heat treated aiming to replace their as-cast structure by a quasi-lamellar one. The respective zirconium partition amongst microconstituents was evaluated, being demonstrated that zirconium concentrates in the γ-phase and increases the volume fraction of this constituent, showing the γ stabiliser role of zirconium.

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“…Therefore the remaining melt contains a higher amount of Al and solidifies at the lower temperature as a dendrite gamma phase. This causes inhomogeneous composition in the microstructure which was reported by other researchers for unalloyed TiAl compound [23]. For removing these inhomogeneities from the microstructure and achieving homogenous duplex and fully lamellar microstructures, solution treatments in the a + g phase region and a-phase region were considered, respectively.…”

Section: Homogenization Processmentioning

confidence: 99%

A Process for Production of a Niobium-containing TiAl Based Alloy

Kamali¹,

Hadi²,

Khalil‐Allafi³

et al. 2010

Canadian Metallurgical Quarterly

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A new generation of turbine engines based on titanium aluminides may be commercially manufactured if these materials could be produced more cheaply and more easily. In the present work, challenges faced during the production of a g-TiAl-based alloy (Ti-48Al-2Cr-2Nb-1B (at%) including the evaporation of aluminum and the formation of niobium-rich inclusions were studied and a set of recommendations has been proposed to overcome them. It was found that TiAl and Nb 3 Al are appropriate master alloys to produce an alloy with a controllable chemical composition and a microstructure free from inclusions without a need for any extra melting processes. A two stage mechanism was found to be responsible for chemical composition variation during the production of the alloy using elemental raw materials: a sharp aluminum loss in the first melting and a moderate one in the second and third melting processes. The first stage can be avoided by using master alloys.It was demonstrated that mechanical properties of an alloy produced after an appropriate heat treatment is comparable to alloys produced by other methods. Prevention of extra melting times has a strong impact on economics and commercialization of these materials.Résumé -On pourrait fabriquer de façon commerciale une nouvelle génération de moteurs à turbine basés sur les aluminures de titane si l'on pouvait produire ces matériaux plus économiquement et plus facilement. Dans le présent travail, on a étudié les défis rencontrés lors de la production d'un alliage basé sur le g-TiAl (Ti-48Al-2Cr-2Nb-1B at%), incluant l'évaporation de l'aluminium et la formation d'inclusions riches en niobium et l'on a proposé une série de recommandations pour les surmonter. On a trouvé que le TiAl et le Nb 3 Al étaient des alliages maîtres appropriés pour la production d'un alliage à composition chimique contrôlable et à microstructure libre d'inclusions sans le besoin de procédés supplémentaires de fusion. On a trouvé qu'un mécanisme à deux étapes était responsable de la variation de la composition chimique lors de la production de l'alliage utilisant des matériaux élémentaires, bruts: une perte élevée d'aluminium lors de la première fusion et une perte modérée lors du deuxième et du troisième procédé de fusion. On peut éviter la première étape en utilisant des alliages maîtres.On a démontré que les propriétés mécaniques d'un alliage fabriqué après un traitement thermique approprié étaient comparables aux alliages produits par d'autres méthodes. L'absence de temps supplémentaire de fusion a un impact important sur l'économie et la commercialisation de ces matériaux.

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As-cast titanium aluminides microstructure modification

Cited by 18 publications

References 9 publications

Electron beam melting of Ti–48Al–2Cr–2Nb alloy: Microstructure and mechanical properties investigation

Electron beam melting of Ti–48Al–2Cr–2Nb alloy: Microstructure and mechanical properties investigation

Zr Bearing γ-TiAl Induction Melted

A Process for Production of a Niobium-containing TiAl Based Alloy

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