We report Magnetic Circular X-ray Dichroism (MCXD) measurements in Fe-
Ni alloys. We used an energy dispersive beamline in our measurements.
A polychromator spectrum contains self reference both in intensity and
energy since all energies are measured at the same time and remain st
able during an energy scan since no movement of the X-ray optics is ne
cessary. We measured the K absorption edges in Fe and Ni (s - p electr
onic states) in the d ferromagnetic alloys of Fe-Ni. We observe that t
he signal at the invar composition is of comparable strengh as other c
ompositions in contrast to previous studies. We used cold rolled (diso
rdered) foils instead of powders. The measurements reveal changes of t
he MCXD signal with composition and crystal structure.