The magnetic behaviour of ThFe3-xAlx of which the parent compound disp
lays re-entrant ferromagnetism, has been studied. Substitution of Al l
eads to an expansion of the lattice which is the largest in the basal
plane. The Curie-temperature decreases monotonously from 428 K for x =
0 to 341 K for x = 0.33. The antiferromagnetic temperature range decr
eases and is completely suppressed for x > 0.33.