Titanium aluminide

Short description: Intermetallic chemical compound

Titanium aluminide  Names

IUPAC name

aluminum;titanium

Identifiers

CAS Number

* 12003-96-2 Y

3D model (JSmol)

* Interactive image

ChemSpider |

* 8466204

PubChem CID

* 10290735

InChI

* InChI=1S/Al.Ti

Key: KHEQKSIHRDRLMG-UHFFFAOYSA-N

SMILES

* [Al].[Ti]

Properties

Chemical formula

| AlTi
Molar mass | 74.849 g/mol

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Infobox references

Titanium aluminide (chemical formula TiAl), commonly gamma titanium, is an intermetallic chemical compound. It is lightweight and resistant to oxidation [1] and heat, but has low ductility. The density of γ-TiAl is about 4.0 g/cm3. It finds use in several applications including aircraft, jet engines, sporting equipment and automobiles.[citation needed] The development of TiAl based alloys began circa 1970. The alloys have been used in these applications only since about 2000.

Titanium aluminide has three major intermetallic compounds: gamma titanium aluminide (gamma TiAl, γ-TiAl), alpha 2-Ti3Al and TiAl3. Among the three, gamma TiAl has received the most interest and applications.

## Contents

* 1 Applications of gamma-TiAl
* 2 Alpha 2-Ti3Al
* 3 TiAl3
* 4 References
* 5 External links

## Applications of gamma-TiAl

Pole figures displaying crystallographic texture of gamma-TiAl in a rolled sheet of alpha2-gamma alloy, as measured by high energy X-rays.[2]

Gamma TiAl has excellent mechanical properties and oxidation and corrosion resistance at elevated temperatures (over 600 °C), which makes it a possible replacement for traditional Ni based superalloy components in aircraft turbine engines.

TiAl-based alloys have potential to increase the thrust-to-weight ratio in aircraft engines. This is especially the case with the engine's low-pressure turbine blades and the high-pressure compressor blades. These are traditionally made of Ni-based superalloy, which is nearly twice as dense as TiAl-based alloys. Some gamma titanium aluminide alloys retain strength and oxidation resistance to 1000 °C, which is 400 °C higher than the operating temperature limit of conventional titanium alloys.[not specific enough to verify][3]

General Electric uses gamma TiAl for the low-pressure turbine blades on its GEnx engine, which powers the Boeing 787 and Boeing 747-8 aircraft. This was the first large-scale use of this material on a commercial jet engine[4] when it entered service in 2011.[5] The TiAl LPT blades are cast by Precision Castparts Corp. and Avio s.p.a. Machining of the Stage 6, and Stage 7 LPT blades is performed by Moeller Manufacturing.[6][citation needed] An alternate pathway for production of the gamma TiAl blades for the GEnx and GE9x engines using additive manufacturing is being explored.[7]

In 2019 a new 55 g lightweight version of the Omega Seamaster wristwatch was made, using gamma titanium aluminide for the case, backcase and crown, and a titanium dial and mechanism in Ti 6/4 (grade 5). The retail price of this watch at £37,240 was nine times that of the basic Seamaster and comparable to the top of the range platinum-cased version with a moonphase complication.[8]

## Alpha 2-Ti3Al

## TiAl3

TiAl3 has the lowest density of 3.4 g/cm3, the highest micro hardness of 465–670 kg/mm2 and the best oxidation resistance even at 1 000 °C. However, the applications of TiAl3 in the engineering and aerospace fields are limited by its poor ductility. In addition, the loss of ductility at ambient temperature is usually accompanied by a change of fracture mode from ductile transgranular to brittle intergranular or to brittle cleavage. Despite the fact that a lot of toughening strategies have been developed to improve their toughness, machining quality is still a difficult problem to tackle. Near-net shape manufacturing technology is considered as one of the best choices for preparing such materials. {date=July 2022}[citation needed]

## References

1. ↑ Voskoboinikov, R.E.; Lumpkin, G.R.; Middleburgh, S.C. (2013). "Preferential formation of Al self-interstitial defects in γ-TiAl under irradiation". Intermetallics 32: 230–232. doi:10.1016/j.intermet.2012.07.026.
2. ↑ "High energy X-rays: A tool for advanced bulk investigations in materials science and physics". Textures Microstruct. 35 (3/4): 219–52. 2003. doi:10.1080/07303300310001634952.
3. ↑ Thomas, M.; Bacos, M. P. (November 2011). "Processing and Characterization of TiAl-based Alloys : Towards an Industrial Scale". Aerospace Lab 3: 1–11. https://hal.archives-ouvertes.fr/hal-01183638/.
4. ↑ "TiAl alloys in commercial aircraft engines". Materials at High Temperatures 33 (4–5): 549–559. 2016. doi:10.1080/09603409.2016.1183068.
5. ↑ "GE Aviation Rolls Out its 1,000th GEnx Engine". 21 October 2015. http://www.aviationpros.com/press_release/12128969/ge-aviation-rolls-out-its-1000th-genx-engine.
6. ↑ Moeller Manufacturing, Aerospace Division, in Wixom, Michigan, USA
7. ↑ Heidi Milkert (18 August 2014). "GE Uses Breakthrough New Electron Gun For 3D Printing – 10X's More Powerful Than Laser Sintering". http://3dprint.com/12262/ge-ebm-3d-printing/.
8. ↑ Tim Barber (31 August 2019). "The new Omega Seamaster Aqua Terra is made of titanium and weighs just 55g". Wired. https://www.wired.co.uk/article/omega-seamaster-aqua-terra-lightest-titanium.

## External links

* Machining Gamma Titanium Aluminide Components - Moeller Manufacturing
* Titanium Aluminide Applications in the HighSpeed Civil Transport
* Titanium Aluminides - Intermetallics on azom.com.
* Power House (GEnx TiAl LPT Blade Announcement)
* Edward A. Loria (2001). "Quo vadis gamma titanium aluminide". Intermetallics 9 (12): 997–1001. doi:10.1016/S0966-9795(01)00064-4.
* Donachie, Matthew J (2000). Titanium: a technical guide. p. 131. ISBN 978-0-87170-686-7. https://books.google.com/books?id=HgzukknbNGAC&pg=PA131.
* Kassner, Michael E; Pérez-Prado, María-Teresa (2004). Fundamentals of creep in metals and alloys. p. 175. ISBN 978-0-08-043637-1. https://books.google.com/books?id=bNfidkEOe-MC&pg=PA175.

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Titanium compounds

Titanium(II)|

* TiCl2
* TiH2
* TiO
* TiS
* TiSi2

| Organotitanium(II) compounds|

[(C5H5)2Ti(CO)2]

|

Titanium(III)|

* TiAl
* TiBr3
* TiCl3
* TiF3
* TiI3
* TiN
* TiP
* Ti2O3
* Ti2S3

| Organotitanium(III) compounds|

[(C5H5)2TiCl]2

|

Titanium(IV)|

* TiB2
* TiBr4
* TiC
* TiCl4
* Ti(ClO4)4
* TiF4
* H2TiF6
* TiH4
* TiI4
* Ti(NMe2)4
* Ti(NO3)4
* TiO2
* H4TiO4
* Ti4(OCH2CH3)16
* Ti(OCH(CH3)2)4
* Ti(OCH2CH2CH2CH3)4
* KTiOPO4
* NiO*Sb2O3*20TiO2
* TiS2
* TiSe2
* TiSi2

| Titanate compounds|

* BaTiO3
* Ba2TiO4
* Bi4Ti3O12
* CaTiO3
* CaCu3Ti4O12
* CaZrTi2O7
* Cs2TiO3
* Dy2Ti2O7
* EuBaTiO4
* FeTiO3
* Ho2Ti2O7
* Li2TiO3
* MnTiO3
* Na2Ti3O7
* Na0.5Bi0.5TiO3
* NiTiO3
* PbTiO3
* Pb(Zr,Ti)O3
* SrTiO3
* ZnTiO3

|

Organotitanium(IV) compounds|

* [(C5H5)2TiCl2]
* [(C5H5)2Ti(CH3)2]
* [(C5H5)2TiS5]
* [(C5H5)2Ti(μ-Cl)(μ-CH2)Al(CH3)2]
* [(η5-C5H4-CH2C6H4OCH3)2TiCl2]

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