Titanium-aluminum, TiAl

Selective solution of the aluminum from the ahoy using a volatile metal, such as mercury, lead, bismuth, cadmium, magnesium, or zinc, has been investigated. After extracting the aluminum from the original ahoy into the volatile metal, the volatile metal is distilled, leaving pure aluminum. Neither electrolysis nor volatile metal extraction can extract aluminum from iron aluniinide [12004-62-3J, EeAl, titanium aluniinide [12004-78-3] TiAl, or Al C. ... 

Metals and ceramics (claylike materials) are also used as matrices in advanced composites. In most cases, metal matrix composites consist of aluminum, magnesium, copper, or titanium alloys of these metals or intermetallic compounds, such as TiAl and NiAl. The reinforcement is usually a ceramic material such as boron carbide (B4C), silicon carbide (SiC), aluminum oxide (A1203), aluminum nitride (AlN), or boron nitride (BN). Metals have also been used as reinforcements in metal matrices. For example, the physical characteristics of some types of steel have been improved by the addition of aluminum fibers. The reinforcement is usually added in the form of particles, whiskers, plates, or fibers. 

Another approach is to select steels that qualify when coated with a coating [2], that either prevents direct contact with the electrolyte and is not oxidized at the cathode. In this respect, ceramic metal nitride coatings are considered (Cr, Ti, TiAl nitride) [78]. If the coating is perfectly dense and stable, any base material could be applied. Alternative base metals being considered are aluminum or titanium [79]. 

The T TiAl phase has an LIq ordered face-centered tetragonal structure (Ref 1-3), which has a wide range (49 to 66 at.% Al) of temperature-dependent stabihty (Ref 1). At the equiatomic TLAl composition, the c/a ratio is 1.02 tetragonality increases up to c/a = 1.03 with increasing aluminum concentration (Ref 4-6). Within the compositional range specified at ofif-stoichiometric compositions, excess titanium or aluminum atoms occupy antisites without creating constitutional vacancies (Ref 7). The y-TLAl phase apparently remains ordered up to its melting point of approximately 1450 °C (2640 °F). 

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