It was recalled that it had been found that 100 to 200MeV heavy-ion irradiation induced a ferromagnetic state in B2-type Fe-50at%Rh intermetallic alloy below the antiferromagnetic-ferromagnetic transition temperature of the unirradiated alloy. In order to characterize the lattice defects induced by swift heavy ion irradiation, Doppler-broadening experiments were performed on unirradiated Fe-Rh alloy, and on material irradiated with 200MeV 136Xe ions, by using a slow positron beam. The S-parameter increased gradually with increasing ion-fluence up to 5 x 1012/cm2. Above 5 x 1012/cm2, the rate of S-parameter increase slowly saturated. From the dependence of the S-parameter upon ion-fluence, the concentration of vacancy-type defects surviving in the specimen was calculated. This was much smaller than that estimated by the TRIM code. The result implied that antisite-type defects remained predominantly in the irradiated specimen, which stabilized the ferromagnetic state in Fe-50at%Rh.

Characterization of Swift Heavy Ion-Induced Defects in Fe-Rh Alloy by using Positron Beam Technique. F.Hori, M.Fukuzumi, A.Kawasuso, Y.Zushi, Y.Chimi, N.Ishikawa, A.Iwase: Physica Status Solidi C, 2007, 4[10], 3530-3