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Micro Fracture Toughness Testing of TiAl Based Alloys with a Fully Lamellar Structure

Published online by Cambridge University Press:  26 February 2011

K. Takashima ,
T. P. Halford ,
D. Rudinal ,
Y. Higo  and
M. Takeyama
K. Takashima
Affiliation:
Precision and Intelligence Laboratory, Tokyo Institute of Technology, R2–35 4259 Nagatsuta, Midori-ku, Yokohama, 226–8503, Japan
T. P. Halford
Affiliation:
Precision and Intelligence Laboratory, Tokyo Institute of Technology, R2–35 4259 Nagatsuta, Midori-ku, Yokohama, 226–8503, Japan
D. Rudinal
Affiliation:
Precision and Intelligence Laboratory, Tokyo Institute of Technology, R2–35 4259 Nagatsuta, Midori-ku, Yokohama, 226–8503, Japan
Y. Higo
Affiliation:
Precision and Intelligence Laboratory, Tokyo Institute of Technology, R2–35 4259 Nagatsuta, Midori-ku, Yokohama, 226–8503, Japan
M. Takeyama
Affiliation:
Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, S8–8 2–12–1 Ookayama, Meguro-Ku, Tokyo, 152–8552, Japan
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Abstract

A micro-sized testing technique has been applied to investigate the fracture properties of lamellar colonies in a fully lamellar Ti-46Al-5Nb-1W alloy. Micro-sized cantilever specimens with a size ≈ 10 × 10 × 50 μm3 were prepared by focused ion beam machining. Notches with a width of 0.5 μm and a depth of 5 μm were also introduced into the micro-sized specimens by focused ion beam machining. Fracture tests were successfully completed using a mechanical testing machine for micro-sized specimens at room temperature. The fracture toughness (KQ) values obtained were in the range 1.4–7 MPam1/2. Fracture surface observations indicate that these variations are attributable to differences in local lamellar orientations ahead of the notch. These fracture toughness values are also lower than those having been previously reported in conventional samples. This may be due the absence of significant extrinsic toughening mechanisms in these micro-sized specimens. Fracture mechanisms of these alloys are also considered on the micrometer scale. The results obtained in this investigation give important and fundamental information on the development of TiAl based alloys with high fracture toughness.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 842: Symposium S – Integrative and Interdisciplinary Aspects of Intermetallics , 2004 , S5.44
Copyright
Copyright © Materials Research Society 2005

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References

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