Effects of aluminum and nitrogen plasma immersion ion implantation on mechanical properties and oxidation resistance of copper

Summary form only given: Plasma immersion ion implantation (PIII) is an effective method to modify the mechanical properties and chemical properties of materials, especially metals. In comparison with conventional ion implantation, PIII can treat samples with complicated shape due to its non-line-of-sight characteristics. The improved mechanical properties can usually be attributed to radiation-enhanced diffusion, ion-induced chemical reactions, grain refinement and defect generation. The technique has been successfully used to improve the hardness, corrosion resistance, oxidation resistance, and even antibacterial properties of different materials. Copper is an important metal in electrical appliances and the chemical industry due to its high electrical conductivity and antibacterial characteristics. However, copper has some practical disadvantages. Firstly, the hardness of pure copper is relatively low. Secondly, copper is not stable in oxygen-containing electrolytes because of dissolution. Thirdly, copper is susceptible to serious oxidation resulting in reduced electrical conductivity and antibacterial performance. In this work, copper is modified by PIII: (i) (0.5~2) times 10¹⁷ ions/cm² of Al at 30 kV and (ii) (0.5~2) times 10¹⁷ ions/cm² of Al at 30 kV and 1times10¹⁷ ions/cm² of N at 30 kV co-implantation. The effects on the hardness and oxidation resistance are studied. Our results indicate that the surface hardness of the Al implanted copper and Al and N co-implanted specimens are 2-3 times better than that of the untreated sample. The thickness of the oxidized layer on the Al and N co-implanted sample decreases dramatically compared to the untreated one. The changes in the corrosion resistance are also investigated. XRD, SEM and XPS are employed to investigate the phase composition, surface morphology, and mechanism of the oxidation resistance.