  Effects of doping on morphology of iron carbide (cementite) nanowires have
been explored by first principle electronic structure calculations. We examined
the role of several realistic impurities (Si, Mn, V, P and S) in the formation
energies of the cementite nanowires with different sizes and morphologies. It
is shown that the presence of the impurities decreases the formation energy and
can switch the preferable axis of the cementite nanowire growth. The conditions
of the formation and decomposition of cementite nanowires in steels are also
discussed.
