Amorphous a-Tb 1−x Fe x alloy films (0.50 ≤ x ≤ 0.90) deposited by co-evaporation in UHV onto Si wafers held at 300 K, have been investigated by conversion electron Mössbauer spectroscopy (CEMS). All a-Tb 1−x Fe x films show preferential (but incomplete) perpendicular Fe spin orientation with average tilting angles 〈Θ〉 ≈ 20–30°, independent of temperature T between 20 K ≤ T ≤ 300 K. The average hyperfine field 〈B hf (0)〉 at saturation was found to depend linearly on x via the relation 〈B hf (0 K)〉 = 39.9T − J · (g − 1) · (1 − x) · 16.3T, where g = 1.5 and J = 6 for Tb 3+ . For x ≥ 0.85 the precipitation of bcc Fe was observed.