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Microstructure and Elevated Temperature Flow Properties of Rapidly Solidified TiAl-Base Alloys

Published online by Cambridge University Press:  26 February 2011

J. A. Graves  and
A. K. Ghosh
J. A. Graves
Affiliation:
Science Center, Rockwell International Corporation, 1049 Camino Dos Rios, Thousand Oaks, CA 91360
A. K. Ghosh
Affiliation:
Dept. of Materials Science and Engineering, Univ. of Michigan, Ann Arbor, MI 48109
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Abstract

Rapid solidification processing (RSP) of TiAl-base alloys often results in the formation of metastable crystalline products (e.g., Ti3Al) A key parameter controlling both the solidification pathway and the stability of the metastable structure is alloy chemistry. This study focuses upon the influence of minor alloy additions on the microstructure and properties of Ti52Al48 alloys produced by RSP. While alloys having minor Ta addi ions (<1 at.%) maintain near-equilibrium solidification structures similar to the binary alloy, the addition of Cr at a level of 5 at.% results in a nearly 100 vol.% metastable Ti3Al structure containing a fine dispersion of TiCr2 grain boundary precipitates. These precipitates limit grain growth during elevated temperature exposure, maintaining the fine (TiAl) grain size created during decomposition of the metastable product structure. Mechanical property evaluation of the consolidated RSP material indicates a greatly reduced flow stress for the fine grained Cr modified alloys. A preliminary analysis attributes this to the reduction in grain size and enhanced elevated temperature diffusion rates for the Cr containing TiAl-base alloys.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 133: Symposium H – High-Temperature Ordered Intermetallic Alloys III , 1988 , 317
Copyright
Copyright © Materials Research Society 1989

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References

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