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Figure 2 shows a selected region of the diffraction pattern of filaments irradiated with
different fluences. The position of the dominant reflection of β-NbTi remains unchanged,
i.e., there is no obvious change of the lattice parameters. The weak reflection of the
equilibrium hcp α-Ti phase decreases already at a low fluence of 3×10 11 ions/cm 2 . By
TEM, we find evidence for the hexagonal ω-Ti phase probably resulting from a transition of
α- into ω-Ti [3]. Neither track formation nor any other phase transition or amorphization of
the β-NbTi phase was detected.
Fig. 2: X-ray diffraction pattern of filaments as function of applied fluence.
Irradiated filaments showed changes of the β-NbTi texture, but quantitative analysis is
problematic due to the small diameter of the filaments. We therefore measured larger foil
samples with a ( 100)[
110]
texture before and after irradiation at a four-circle
diffractometer. Comparing their pole figures gives evidence of irradiation-induced
degradation and rotation of the azimuthal distribution of the (100) planes (Fig. 3).
Fig. 3: (100) pole figures of NbTi-foil (left: virgin, right: irradiated with 10 12 cm -2 U ions).
References
[1] L. Latysheva, N. Sobolevskiy, G. Moritz, E. Mustafin, G. Walter, GSI Scientific Report
2003 (May 2004) p. 252.
[2] S.T. Sekula, J. Nucl. Mat. 72 (1978) 91.
[3] H. Dammak, A. Dunlop, D. Lesueur, Nucl. Instr. Meth. B 107 (1996) 204.
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