LAMMPS has a pair_style eam. It takes EAM potential
files as input. So if you can find/provide an EAM file
for Pb and Fe, then you can use it. LAMMPS can mix
the two to create alloy interactions. But LAMMPS doesn't
generate EAM interaction out of thin air. You have to
provide those input files. See the EAM doc page for WWW
sites that have them for various materials.
Steve