The role of ion-induced segregation on the surface damage of alloys during sputtering at elevated temperatures

Surface ion damage was studied for Cu/Ni, Au/Cu, Ag/Cu, Co/Ni, and Fe/Ni alloys during noble gas ion bombardment at elevated temperatures. Tests were also made for a coarse-grained Cu/Ni alloy at liquid nitrogen temperature. Results related to the effect of surface segregation on (a) the angular distribution of the sputtered atoms, and (b) the grain boundary erosion are presented. It was found that the segregated atoms have a tendency to be sputtered preferentially in the direction of the target surface for the case of Cu/Ni, and Co/Ni alloy at elevated temperatures. Such a tendency was observed for the sputtering of Cu/Ni alloy even at 100 K. However, it was not observed for Au/Cu, Ag/Cu, although the segregation phenomena were drastically observed. After sputtering of the Cu/Ni alloys at 873 K, the grain boundaries were no longer straight and some had developed zigzag shapes 2-3 μm in width. The cross section of the specimen showed the existence of large voids of 20-30 μm in depth and 3-5 μm in width just beneath the eroded grain boundaries, presumably due to the ion induced Kirkendall effect (IKE) .