Iron in NiAl intermetallic compound: atomic arrangements and associated magnetic properties and electronic structures

Abstract

Measurements of magnetic susceptibility and 27Al nuclear magnetic resonance (NMR) were carried out for NiAl intermetallic compounds alloyed with Fe (up to 10 at%). Alloying was performed for Ni-rich, Al-rich and stoichiometric compounds by substituting for Ni or Al, or both Ni and Al. Changes in magnetism from Pauli to Curie-Weiss type, and appearance of new lines in NMR spectra, were determined to be due to the alloying. Variations in atomic arrangements and related magnetic properties and electronic structures of alloyed NiAl were considered. Experimental results were compared with those obtained by computer calculations of the cluster electronic structures. NMR results indicate that Fe atoms are not distributed randomly in the lattice. Site preferences of Fe were considered for different compounds. Increase in density-of-states at the Fermi level was established by the substitution of Fe for both Ni and Al atoms. Finally, the mechanical properties in compression of alloys at room temperature were compared with data on atomic structure changes with alloying.