Mössbauer Spectroscopy studies of some intermetallics in the Zr-Nb-Fe system

C. P. RAMOS; C. SARAGOVI; M. GRANOVSKY; D. ARIAS

Virginia

Simposio; Int. Symposium on the Industrial Applications of Mössbauer Spectroscopy (ISIAME 2000); 2000

Zr-Nb alloys are used in the pressure tubes of the CANDU-type nuclear power plants. Being Fe a fast diffusive element in Zr, it can be present as a minor component. Likewise, the multicomponent Zr-based alloys, with Sn, Nb, Fe and O, i.e. Zyrlo are being investigated as possible structural constituents of reactors. These materials present Zr-Nb-Fe precipitates. In any case, the knowledge of the mentioned ternary system is of paramount importance for the nuclear power industry. The Zr-Fe-Nb diagram has been barely studied [1] at variance with binary phase diagrams (Zr-Fe [2], Zr-Nb [3] and Fe-Nb [4]) which have been extensively studied. We present results on as cast and heat-treated Zr62Nb14Fe24, Zr65Nb10Fe25 and Zr52Nb10Fe38 samples to continue previous studies on this ternary system [5].  Mössbauer spectroscopy of 57Fe was used on these six samples and results are complemented with XRD (X-ray diffraction) and EM (electron microprobe analysis) [6]. All spectra were analyzed with overlapping doublets. Zr62Nb14Fe24 and Zr65Nb10Fe25 spectra showed two major doublets assigned to Zrb and to a cubic Ti2Ni type [5] phase and traces corresponding to a hexagonal MgZn2 type phase. Zr52Nb10Fe38 spectra also showed two major doublets assigned to a cubic Ti2Ni type  phase and to the hexagonal MgZn2 type phase. The corresponding assignments contribute to a better understanding of this region of the diagram. [1] Phase Diagrams of Ternary Fe Alloys, 6, Indian Inst. of Metals, p. 1031, (1992). Z.M. Alekseeva and N.V. Korotkova, Izvestiya Ak. Nauk SSSR. Metally 1, p.199, (1989). N.V. Korotkova and Z.M. Alekseeva, Izvestiya Ak. Nauk SSSR. Metally 3, p.207, (1989). [2] D. Arias, M. Granovsky and J. Abriata, in: ASMI, Mat. Park, ed. H. Okamoto, p. 467, (1993). [3] A. Perovic and G. Weatherly, J. Phase Equilibria 18 (3), p. 245, (1997). [4] H. Okamoto, J. Phase Equilibria 14 (5), p.650, (1993). [5] C. Ramos, C. Saragovi, M. Granovsky and D. Arias, Hyp. Int. 122, p. 201, (1999). [6] E. Lena, Master Thesis in Mat. Science and Tech., Inst. de Tecnología, CNEA, (1998).