Effect of Al-plasma based ion implantation on the composition and phase structure of AgMgNi alloy surface

Al-plasma based ion implantation (Al-PBII) into AgMgNi alloy is carried out using metal plasma generated from the unbalanced magnetron sputtering (UBMS) and RF stimulating. The depth profile and the chemical states of Al and O are analyzed using XPS. The phase structures of the samples before and after the implantation are determined by XRD analysis. The results show that an Al implantation layer appears on the surface of AgMgNi alloy substrates and the concentration of Al decreases gradually as the depth increases. There are three chemical states of Al in the implantation layer: pure Al, Al in solid solution and as Al2O3 and two chemical states of oxygen, i.e. solid solved oxygen and oxygen in Al2O3. The effect of the distance from magnetron target to substrates (Ds−t) on the surface structure has also been studied. Comparing the surface structures before and after implantation shows that: with a shorter Ds−t of 200 mm, the lattice constant α of the Ag phase in the implantation layer of AgMgNi alloy substrate decreases, while the intensity of the peak defined as the (311) plane increases; when Ds−t is increased to 300 mm, the lattice constant α increases with no significant change of the intensity of the peak of any plane. At a moderate Ds−t of 250 mm, no significant change of α can be detected, but the intensity of the peak defined as (311) increases. The reason for the changes of the surface structure of AgMgNi alloy is the formation of an Ag–Al implantation layer and the collision cascades of Ar+ in the surface of the substrate.