J. Phys. Colloques
Volume 51, Numéro C4, Juillet 1990Multilayer Amorphisation by Solid-State-Reaction and Mechanical Alloying
|Page(s)||C4-189 - C4-195|
J. Phys. Colloques 51 (1990) C4-189-C4-195
PHASE TRANSFORMATIONS OF SUPERSATURED SPUTTERED Nb Co FILMSW. BIEGEL1, W. SCHAPER1, H.-U. KREBS1, J. HOFFMANN1, H.C. FREYHARDT1, R. BUSCH1 et R. BORMANN2
1 Institut für Metallphysik, Universität Göttingen, Hospitalstrasse 3/5, D-3400 Göttingen, F.R.G.
2 Forschungszentrum Geesthacht GmbH (GKSS), Max-Planck-Strasse, D-2054 Geesthacht, F.R.G.
Supersaturated NbCo thin films were prepared in the concentration range 4 -15 at.% Co by triode co-sputtering. Based on thermodynamic calculations (CALPHAD) for the Nb-Co system, we expect during heating a transformation of the supersaturated bcc NbCo phase into a metastable two-phase system of bcc NbCo and an amorphous phase, and for temperatures above 750°C, the crystallization into the equilibrium phases. Structure and structural transformation of the annealed supersaturated NbCo phase were studied by means of X-ray diffraction and transmission electron microscopy. The kinetics of the phase formation could be investigated by in-situ X-ray diffraction experiments at constant temperature of 600°C. The shift of the NbCo-(110) peak position obeys a [MATH] law, indicating a linear decrease of the Co concentration in the NbCo phase with [MATH]. The superconducting transition temperature and the critical current of the films were used as a probe to detect precipitations and to determine the concentration of the NbCo phase.