Sputtering and secondary ion yields of TiAl alloys subjected to oxygen ion bombardment

Total sputtering and secondary ion yields of single phase TiAl alloys containing 0–35 at% Al under oxygen ion bombardment were measured for thin film targets with known thicknesses and compositions. It was found that the total sputtering yield initially decreased with increasing Al content and became constant beyond 20 at% Al. On the other hand, the secondary ion yield of Al roughly increases with increasing Al content, while that of Ti shows a complementary decrease. Their variations, however, show a large flucutation with Al content. Detailed observations revealed that the secondary O₂ ion yield also exhibited the same pattern of fluctuation as that of Al and Ti. The modified degrees of ionization of both Al and Ti in the consideration for the secondary oxygen ion yield indicated an exponential dependence upon the alloy composition. The trends of the modified degrees of ionization revealed that the matrix effect due to the alloy composition affected more strongly on Ti than on Al.