Lorentz microscopy and magnetization and Mo¨ssbauer effect measurements have been performed on a Cr‐Co‐Fe alloy having a two‐phase microstructure. Domains spanning many particles have been seen in samples whoseHc’s vary between 200 and 420 Oe. Walls appear to be ragged and are held back by particles. Magnetization and Mo¨ssbauer effect measurements indicate that the two phases constituting the microstructure in each of the three situations examined are ferromagnetic at ambient temperature. Based on these results it is inferred that domain‐wall–particle interaction is responsible forHc.