Effects of cascade energy density on radiation induced segregation and ion beam mixing

The effects of cascade energy density on two ion-beam induced phenomena, radiation-induced-segregation (RIS) in near-surface regions and ion-beam of thin surface layers, were investigated. RIS of Si to external surfaces of Ni-12.7 at.% Si alloys was measured for 2.75 MeV Kr and 1.5 MeV He bombardments. The Kr irradiation produces defects mostly in energetically dense displacement cascades, whereas the He irradiation produces most of the defects in low energy recoils. Thin Pt and Ni layers deposited on (111) oriented Si surfaces were ion-beam mixed using 8O keV Ne and 28O keV Kr irradiations. Dense cascades were found to inhibit RIS, but to enhance ion-beam mixing. (orig.)