High-field magnetization curves of Tb2Fe17 and Er2Fe17 at 4.2 K are an
alyzed in terms of the R-Fe exchange and the crystal field interaction
s. The observed first-order magnetization processes along the c-axis f
or Tb2Fe17 and along the a, b and c-axes for Er2Fe17 are well reproduc
ed by the calculation. Several field-induced phase transitions in Er2F
e17 in the high-field region are predicted.