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Fatigue crack initiation at Nd-rich particles in an Nd containing high temperature titanium alloy

Published online by Cambridge University Press:  31 January 2011

J. F. Lei
Affiliation:
State Key Laboratory for Fatigue and Fracture of Materials, Institute of Metal Research, Academia Sinica, Shenyang 110015, People's Republic of China
Q. J. Wang
Affiliation:
State Key Laboratory for Fatigue and Fracture of Materials, Institute of Metal Research, Academia Sinica, Shenyang 110015, People's Republic of China
Y. Y. Liu
Affiliation:
State Key Laboratory for Fatigue and Fracture of Materials, Institute of Metal Research, Academia Sinica, Shenyang 110015, People's Republic of China
S. X. Guan
Affiliation:
State Key Laboratory for Fatigue and Fracture of Materials, Institute of Metal Research, Academia Sinica, Shenyang 110015, People's Republic of China
Z. G. Wang
Affiliation:
State Key Laboratory for Fatigue and Fracture of Materials, Institute of Metal Research, Academia Sinica, Shenyang 110015, People's Republic of China
D. Li
Affiliation:
State Key Laboratory for Fatigue and Fracture of Materials, Institute of Metal Research, Academia Sinica, Shenyang 110015, People's Republic of China
Z. Q. Hu
Affiliation:
State Key Laboratory for Fatigue and Fracture of Materials, Institute of Metal Research, Academia Sinica, Shenyang 110015, People's Republic of China
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Abstract

Scanning electron microscopy (SEM) and surface replica method have been employed to study the micromechanism of fatigue crack initiation at Nd-rich phase particles in a high temperature titanium (Ti-55) alloy. It was found that the microcrack initiates near the equator of Nd-rich particles in the matrix. The microcrack grows first at an angle of about 45° with respect to the tensile axis, and then its growth direction becomes approximately normal to the tensile axis. The experimental results are analyzed in terms of the elastic stress distribution around soft particles imbedded in the matrix to account for the experimental findings of particle cracking and the associated surface microcrack initiation near the particle “equator.” A model of fatigue crack initiation at a soft surface particle is proposed.

Type
Articles
Copyright
Copyright © Materials Research Society 1997

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References

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