Ion bombardment effects in the sputtering of single- and two-phase brass alloys; Cu:18-48% Zn

The effect of ion bombardment on the near-surface composition of brass has been investigated over a bulk composition range including single-phase α (fcc) brass and two-phase, α + β (bcc) brass. Auger electron spectroscopy has been used to determine the equilibrium near-surface composition after ion sputtering with argon and xenon at ion energies between 1 and 4 keV. Preferential removal of the zinc was found under all conditions. X-ray photoelectron spectroscopy has been used to investigate variations in composition in the first atomic layers by comparison of the intensities and escape depths of the 2p and 3p photoemission peaks. The near-surface composition was primarily a function of ion energy in the single α phase, with higher ion energy increasing the preferential removal of zinc; no change was detected comparing data from information depths of 5 vs. 10 monolayers. In the mixed α + β phase, surface zinc concentration decreased with increasing ion energy and mass, and depletion of zinc was greater nearer to the surface. (author)