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Effect of Thermomechanical Treatments on Solidification Inhomogeneity in Ingot Metallurgy Gammtait Anium Aluminides

Published online by Cambridge University Press:  21 February 2011

J. D. Bryant ,
S. L. Semiatin ,
J. R. Maisano ,
D. T. Winter  and
A. R. H. Barrett
J. D. Bryant
Affiliation:
Martin Marietta Laboratories, Baltimore, MD
S. L. Semiatin
Affiliation:
Battelle Memorial Institute, Columbus, OH.
J. R. Maisano
Affiliation:
Martin Marietta Laboratories, Baltimore, MD
D. T. Winter
Affiliation:
Martin Marietta Laboratories, Baltimore, MD
A. R. H. Barrett
Affiliation:
Martin Marietta Laboratories, Baltimore, MD
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Abstract

The addition of titanium diboride to near gamma titanium aluminides has been effective in reducing the initial grain size formed on solidification from the melt. Despite this refinement, however, significant constitutional inhomogeneity may be found due to segregation of alloying elements and reinforcement phases during solidification. The dendritic solidification of several XD'T alloys was studied to assess the extent of this segregation. Quantitative elemental analysis of dendritic and interdendritic regions indicates that a substantial chemical gradient is developed in aluminum and ternary alloying elements. The extent of chemical and reinforcement segregation and its relationship to overall aluminum content in the alloys is discussed. In a study to determine thermomechanical processing steps required to eliminate the casting inhomogeneity, homogenization heat treatments and isothermal forging were performed and the effect on microstructure determined. Remnant dendritic cell structures were seen to persist despite high-temperature heat treatments and mechanical working.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 194: Symposium R – Intermetallic Matrix Composites I , 1990 , 59
Copyright
Copyright © Materials Research Society 1990

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References

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