Microstructure and chemical homogeneity of plasma-arc cold-hearth melted Ti-48Al-2Mn-2Nb gamma titanium aluminide

Conference · Sun Dec 31 00:00:00 EST 1995

OSTI ID:225120

Dowson, A L; Johnson, T P; Young, J M; Jacobs, M H ^[1]

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1. Univ. of Birmingham, Edgbaston (United Kingdom). IRC in Materials for High Performance Applications

The microstructure and chemical homogeneity of plasma-arc cold-hearth (PACH) melted Ti-48Al-2Mn-2Nb gamma-based titanium aluminide have been studied and potential correlation`s between compositional variations and changes in both the withdrawal rate and the crucible torch current have been explored. Periodic oscillations in composition have been identified both across the ingot cross section and down the length of the bar, and distinct regions involving both Al enrichment and depletion have been identified, primarily towards the edge and near central regions of the bar. These changes in composition were accompanied by a change in the microstructural morphology with the microstructure changing from a relatively fine, fully equiaxed gamma phase morphology at the surface, through coarse columnar, to a heavily cored dendritic-type structure on moving towards the centre of the bar. Micro-analytical studies of this dendritic region have shown the primary and secondary dendrite arms to consist of a fully transformed lamellar structure relatively rich in both Ti and Nb with Mn and Al tending to segregate preferentially to the interdendritic regions.

• OSTI ID: 225120
• Report Number(s): CONF-950201-; ISBN 0-87339-304-X; TRN: IM9621%%50
• Resource Relation: Conference: Annual meeting and exhibition of the Minerals, Metals and Materials Society (TMS), Las Vegas, NV (United States), 12-16 Feb 1995; Other Information: PBD: 1995; Related Information: Is Part Of Gamma titanium aluminides; Kim, Y.W. [ed.] [UES, Inc., Dayton, OH (United States). Materials and Processes Div.]; Wagner, R. [ed.] [GKSS Research Center, Geesthacht (Germany). Inst. for Materials Research]; Yamaguchi, Masaharu [ed.] [Kyoto Univ. (Japan). Dept. of Materials Science and Engineering]; PB: 1023 p.
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
33 ADVANCED PROPULSION SYSTEMS
TITANIUM ALLOYS
CASTING
MICROSTRUCTURE
ALUMINIUM ALLOYS
MANGANESE ALLOYS
NIOBIUM ALLOYS
GAS TURBINE ENGINES
MATERIALS
INTERMETALLIC COMPOUNDS
PLASMA HEATING
MELTING
CHEMICAL COMPOSITION
OPTICAL MICROSCOPY
ELECTRON MICROPROBE ANALYSIS
EMISSION SPECTROSCOPY
MORPHOLOGY
LAMELLAE
DENDRITES
SEGREGATION