Mössbauer effect measurement evidence for magnetic transition in ordered Fe-doped NiAl

Mössbauer effect measurements at room and cryogenic temperatures on powdered Fe-doped NiAl materials (designated as Ni–40Al–9Fe and Ni–50Al–9Fe) show that both were paramagnetic down to17 K, displaying one Fe site in the host. At 4.2 K, Ni–40Al–9Fe remained paramagnetic, while Ni–50Al–9Fe showed a magnetic transition, with a clearly resolved Fe environment. The determined internal magnetic field was 185 ± 8 kOe in comparison to 330 kOe for α-Fe (bcc) reference at room temperature. This shows that development and evolution of electronic and magnetic interactions associated with the dopant Fe in the ordered NiAl depend on its site preference tendencies. The temperature dependence of magnetic state of the dopant Fe, in conjunction with its site preference tendencies from Mössbauer effect measurements, confirms the effectiveness of this technique in the study of the hardening/softening behaviors of Fe-doped NiAl.