title: Synthesis, Crystal Structure, Magnetic Properties, and Stability of the Manganese-Rich "Mn3AlC" κ Phase.
abstract: κ-carbides of varying composition, seemingly responsible for age hardening in high-Al steel alloys, have been detected to precipitate both at grain boundaries and in the bulk grain of steels. Herein we report the bulk-phase synthesis of "Mn3AlC" by arc plasma sintering and rapid solidification. Single crystals have been found suitable for X-ray diffraction using Mo radiation and yield a lattice parameter of a = 3.875(2) Å. We find a mixed occupation of the 1a position by Al and Mn, which, together with the C position being fully occupied, leads to the actual composition Mn3.1Al0.9C. Additional energy-dispersive X-ray-scanning electron microscopy measurements support the composition and corroborate the homogeneity. SQUID data collected on the polycrystalline ferromagnetic sample exhibit a Curie temperature of about 295 ± 13 K and a soft magnetic behavior. The small but significant nonstoichiometry on 1a leads to a slightly larger lattice parameter, a higher electron count, and, thus, a lowered density of states at the Fermi level, indicative of increased phase stability.
authors.affiliation: Institute of Inorganic Chemistry, RWTH Aachen University , Landoltweg 1, D-52056 Aachen, Germany.
authors.forename: Hannes
authors.initials: H
authors.lastname: Dierkes
authors.affiliation: Institute of Inorganic Chemistry, RWTH Aachen University , Landoltweg 1, D-52056 Aachen, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: van Leusen
authors.affiliation: Institute of Inorganic Chemistry, RWTH Aachen University , Landoltweg 1, D-52056 Aachen, Germany.
authors.forename: Dimitri
authors.initials: D
authors.lastname: Bogdanovski
authors.affiliation: Institute of Inorganic Chemistry, RWTH Aachen University , Landoltweg 1, D-52056 Aachen, Germany.
authors.forename: Richard
authors.identifier: http://orcid.org/0000-0002-1925-9624
authors.initials: R
authors.lastname: Dronskowski