The structure and magnetic properties of ultra-thin Fe spacer layers in epitaxially sputter-deposited Fe/Ni(0 0 1) multilayers are studied using X-ray diffraction and squid magnetometry, and compared to those of similarly deposited Fe/Ni₈₁Fe₁₉(0 0 1) multilayers. In both systems, the Fe layers undergo a similar sequence of structural changes with increasing Fe thickness, from a distorted FCC(0 0 1) phase, to a nearly relaxed FCC(0 0 1) phase, to a BCC(0 1 1) phase with concomitant changes in magnetic properties.