Effects of fluence and fluence rate of proton irradiation upon magnetism in Fe₆₅Ni₃₅ Invar alloy

Curie temperature, T_C, of the Fe-Ni Invar alloys increase due to irradiation with electron and some kinds of ions. In this study, proton irradiation effects upon magnetism in an Fe₆₅Ni₃₅ alloy have been investigated. It is found that the increment of T_C, ∆T_C, increases with increasing fluence. The magnetic hysteresis curve of the alloy was found to be unaffected by irradiation. Comparing ∆T_C and the calculated energy transfer from the ions to the sample, it seemed that ∆T_C was found to be related to the number of vacancies formed in nuclear collision events. In addition, ∆T_C was influenced by the fluence rate, i.e., the deposited energy per unit time. - Highlights: • Proton irradiation effect on T_C of Fe₆₅Ni₃₅ was investigated. • Increment of T_C, ∆T_C, was confirmed in ion passed through and stopped samples. • The relationships among ∆T_C and the deposited energy and vacancies were discussed. • It was reasonable to consider that ∆T_C was related to the number of vacancies. • ∆T_C was influenced by fluence rate, i.e. the energy deposition rate