Investigation into sputtering of aluminium alloys under ion bombardment

Aluminium (99.99%) and Al-3% Li alloy samples were irradiated with 2.5 KeV argon and helium ions, ion current density being 200 μA/cm2 and the temperature of 300 deg C. Change of sample mass during sputtering was determined by gravimetric method. Al-3% Li alloy sputtering coefficient during irradiation with argon ions is reduced by a factor of 1.4, as compared to aluminium, and during irradiation with helium ions - by a factor of 2.4. Being applied to the sample with negative in reference to the chamber walls 50 V potential the alloy sputtering coefficient is decreased by 4 fold in comparison with pure aluminium. Observed effect is associated with lithium radiation-stimulated segregation resulting in sufficient enrichment of the surface with the light element - lithium. Secondary ion mass-spectrometry investigation showed that enriched layer is capable of continuous restoration during sputtering; this fact is important in practical use of aluminium-lithium alloys as a first wall material for plasma plants