We measured Mossbauer spectra from bcc alloys of compositions near Fe3
Al, Fe3Si, and Fe3Ge, and reanalyzed older data from Fe3Ga. All four a
lloys developed some D0(3) chemical order, and their Mossbauer spectra
were qualitatively similar. The local (first-nearest-neighbor) could
be distinguished from the nonlocal (beyond the first-nearest-neighbor)
contributions to the Fe-57 isomer shifts from the solute atoms owing
to differences in their hyperfine magnetic fields. The nonlocal isomer
shift contributions correlated best to the valence of the solute atom
, and not to the atomic volume. The local isomer shift contributions w
ere best attributed to a loss of Fe 3d electrons at the solute sites.