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Influence of Microstructure Refinement on Strength, Ductility and Toughness of TiAl Alloys

Published online by Cambridge University Press:  15 February 2011

M. A. Morris  and
M. Leboeuf
M. A. Morris
Affiliation:
Institute of Structural Metallurgy, University of Neuchâtel, Av. Bellevaux 51, Neuchâtel, SWITZERLAND.
M. Leboeuf
Affiliation:
Institute of Structural Metallurgy, University of Neuchâtel, Av. Bellevaux 51, Neuchâtel, SWITZERLAND.
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Abstract

Different Ti-Al alloys with grain sizes ranging from 7μm to 320 nm have been prepared by consolidation of atomised and mechanically milled powders of nominal composition Ti-48Al-2Mn-2Nb and containing carbon additions. The materials obtained consist of equiaxed γ grains containing a distribution of α2 phase mostly along grain or powder boundaries. The high flow strength and low fracture toughness obtained from these materials have been correlated to the fine scale of the microstructure and the transfer of slip across adjacent γ grains. The existence of stress concentrations at boundaries between γ grains leads to emission of curved dislocations and twins. The low mobility of emitted dislocations is responsible for the lack of tensile ductility in these alloys which fail by microcrack formation at grain boundaries.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 460: Symposium Z – High-Temperature Ordered Intermetallic Alloys VII , 1996 , 177
Copyright
Copyright © Materials Research Society 1997

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References

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