Structural and Mossbauer spectroscopic investigation of Fe substituted Ti-Ni shape memory alloys

In the present investigation the effect of Fe substitution in Ti(51)Ni(49) alloy has been studied. The alloys were synthesized through radio frequency induction melting. The alloy was characterized through X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Mossbauer spectroscopy and positron annihilation techniques. It was found that the Fe substitution stabilized the TiNi type cubic (a = 2.998 angstrom) phase. The microstructure and presence of the oxide phase in Ti(51)Ni(45)Fe(4) alloy have been investigated by scanning electron microscopy. The positron annihilation measurements indicated a similar bulk electron density in both the as-cast and annealed (1000 degrees C for 30 h) alloys, typically like that of bulk Ti. Mossbauer spectroscopy studies of as-cast and annealed iron substituted samples showed regions in the samples where nuclear Zeeman splitting of Fe levels occurred and an oxide phase was found to be present in as cast Ti(51)Ni(45)Fe(4) alloy, while annealed sample indicated the presence of bcc iron phase. (C) 2009 Elsevier B.V. All rights reserved.