The states of order and the phase diagram of Fe[sub 1[minus]x]Si[sub x], 0. 06 [le] x [le] 0. 20, investigated by neutron scattering

The states of order of iron-silicon solid solutions with atomic fractions c of silicon between 0.06 and 0.2 have been studied in neutron scattering experiments. Up to 873 K, Fe0.06Si is short-range ordered. The structures of the other alloys can be described as follows. They are DO[sub 3] long-range ordered at far lower c and higher temperatures than indicated in the current phase diagram: e.g. Fe-0.099Si up to at least 900 K and Fe-0.197Si up to at least 1,473 K. The DO[sub 3]-order parameter as well as the size of the antiphase domains decrease as the temperature is raised. Some phase boundaries shown in the current phase diagram turn out to be no phase boundaries at all; the respective lines have bearing only on the size of antiphase domains. Revisions of the current Fe-Si phase diagram are proposed.