1 research outputs found
Lezione 8
Îş-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 “Mn<sub>3</sub>AlC” 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 <i>a</i> = 3.875(2) Ă…. We find a mixed occupation
of the 1<i>a</i> position by Al and Mn, which, together
with the C position being fully occupied, leads to the actual composition
Mn<sub>3.1</sub>Al<sub>0.9</sub>C. 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 1<i>a</i> 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