Mossbauer spectroscopy characterization of Zr-Nb-Fe phases

The aim of this work was the characterization of the ternary phases and of those coming from the corresponding binary systems in the Zr-Nb-Fe diagram by means of Mossbauer spectroscopy. This is part of a complete study involving a tentative isothermal section at 900 degrees C of the center of the Zr-Nb-Fe diagram which will be published elsewhere. Zr-Nb-Fe alloys with Nb contents between 5 and 50 at% and Fe contents between 10 and 60 at% were analyzed after a heat treatment at 900 degrees C for 4 month. Mossbauer characterization of the phases was complemented by optical and scanning electron microscopies, Xray diffraction and electron microprobe analysis. From the obtained results it can be inferred that Fe in both of the Laves phases present in this system (Zr(FeNb)(2) and (ZrNb)Fe-2) sees different environments, producing quadrupole splitting and hyperfine field distributions, respectively. Two types of body centered cubic beta phases (Zr-rich and Nb-rich) were found having noticeable differences in their Mossbauer parameters. Furthermore it was shown that the ternary Fe(NbZr)(2) compound would show magnetic character at low temperatures. Concentration dependence of the hyperfine parameters and their relations with the lattice parameters contributed to the structural characterization of the phases. (c) 2006 Elsevier B.V. All rights reserved.