Titanium aluminide

Applications of gamma-TiAl

|doi-access=free 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.

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{{ cite journal |access-date= 10 August 2017

Alpha 2-{{chem2|Ti3Al}}

Alpha 2- is an intermetallic compound of titanium and aluminum, belonging to the Ti-Al system of advanced high-temperature materials. It is primarily used in aerospace and other high-performance applications due to its balance of strength, lightweight properties, and oxidation resistance.

It has an ordered hexagonal (D019) crystal structure, which makes it distinct from the more commonly known γ-TiAl (gamma titanium aluminide).

{{chem2|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 1000 C. However, the applications of 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 , 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.

References

References

1. (November 2011). "Processing and Characterization of TiAl-based Alloys : Towards an Industrial Scale". Aerospace Lab.
2. [http://www.moeller-aerospace.com/specialties/titanium-aluminide Moeller Manufacturing, Aerospace Division, in Wixom, Michigan, USA]