Accession Number : ADA320466

Title :   Low Temperature Chemical Routes to Synthesis and Processing of Titanium Aluminides Intermetallics.

Descriptive Note : Final rept. 15 Dec 94-14 Apr 96,

Corporate Author : CARNEGIE-MELLON UNIV PITTSBURGH PA DEPT OF MATERIALS SCIENCE AND ENGINEERING

Personal Author(s) : Kumta, Prashant N.

PDF Url : ADA320466

Report Date : 14 JUN 1996

Pagination or Media Count : 30

Abstract : The goal of this project was to synthesize gamma-TiAl using low temperature chemical processing techniques. Four different chemical processes based on the electropositive and reducing power of lithium were used to investigate their potential for the synthesis of the aluminides. The reactions conducted in polar solvents resulted in the formation of TiAl along with TiC as a secondary phase. Among the various polar solvents attempted, THF appears to be the most suitable solvent since the carbide phase was very much reduced. It also appears from these preliminary studies that subjecting the precursors to pre-treatment in H2 makes them stable towards oxidation. Washing the preheated powders in water at this stage helps in minimizing and even elimination to a large extent impurity phases which may be related to lithium. The uses of inert solvents were found to be unsuitable due to the formation of insoluble adducts that lead to the generation of the formation of unknown phases in addition to TiC. The presence of TiC as an impurity is related to the coordination of TiCl with the solvent. The process offers promise and future efforts should be concentrated on removal of the solvent molecules coordinated to the metal groups so that single phase gamma-TiAl can be synthesized. At the same time, it is possible that these TiAl-TiC composites may have some potential structural application.

Descriptors :   *LOW TEMPERATURE, *TITANIUM, *INTERMETALLIC COMPOUNDS, *ALUMINIDES, METALS, SYNTHESIS, MOLECULES, STRUCTURAL PROPERTIES, WATER, POWDERS, CARBIDES, IMPURITIES, PHASE, HYDROGEN, LITHIUM, OXIDATION, CHEMICAL REACTIONS, HEATING, SOLVENTS, INERT MATERIALS, POLARITY, ELIMINATION, REDUCTION(CHEMISTRY).

Subject Categories : Inorganic Chemistry
      Atomic and Molecular Physics and Spectroscopy
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE