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The Deformation and Dynamic Recrystallization in a Hot Isostatically Pressed Ti-48A1-2W Powder Alloy

Published online by Cambridge University Press:  01 January 1992

L. Zhao ,
J. Beddoes  and
W. Wallace
L. Zhao
Affiliation:
Structures and Materials Laboratory, Institute for Aerospace Research, National Research Council Canada, Ottawa, Canada
J. Beddoes
Affiliation:
Department of Mechanical and Aerospace Engineering, Carleton University, Ottawa, Canada
W. Wallace
Affiliation:
Structures and Materials Laboratory, Institute for Aerospace Research, National Research Council Canada, Ottawa, Canada
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Abstract

Titanium aluminide powder of composition Ti-48A1-2W (at%) was consolidated by hot isostatic pressing (HIP) at 200 MPa and 1050°C, 1100°C, 1150°C and 1250°C, respectively. The as-HIP'ed microstructure and substructure were characterized by optical microscopy and transmission electron microscopy (TEM). The densified powder alloy possesses an inhomogeneous microstructure consisting of fine-grained prior dendrites and coarse-grained interdendritic regions. The former contain the , 2 and phases. The HIP processing induced substantial deformation in the latter regions where dislocation segments and tangles, deformation twins and dislocation sub-boundaries were formed, indicative of plastic yielding and creep deformation. Both 1/2<110] unit dislocations and superdislocations are activated during HIP, but the former are the predominant dislocations in the sub-boundaries. With increasing HIP temperature, dynamic recrystallization occurs to a greater extent, resulting in a relatively uniform microstructure. The microstructure can be divided into hard and soft regions in which the densification is dominated by different mechanisms. Methods of optimizing the HIP cycle parameters to produce a more homogeneous microstructure are discussed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 288: Symposium L – High-Temperature Ordered Intermetallic Alloys V , 1992 , 921
Copyright
Copyright © Materials Research Society 1995

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References

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