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

Curie temperature, TC, 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 TC, ∆TC, increases with increasing fluence. The magnetic hysteresis curve of the alloy was found to be unaffected by irradiation. Comparing ∆TC and the calculated energy transfer from the ions to the sample, it seemed that ∆TC was found to be related to the number of vacancies formed in nuclear collision events. In addition, ∆TC was influenced by the fluence rate, i.e., the deposited energy per unit time.