Regensburg 2010 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 9: Poster: Synthesis of Nanostructured Films by Self-organization, Thermoelectric Thin Films and Nanostructures, High-k and Low-k Dielectrics, Layer Deposition Processes, Layer Growth, Layer Properties, Application of Thin Films, Surface Modification, Hard and Superhard Coatings, Metal Layers

DS 9.16: Poster

Montag, 22. März 2010, 15:00–17:30, Poster D1

XPS Analysis of Phase Formation after Nitrogen Insertion in CoCr and FeCrNi Alloys — •Johanna Lutz^1,2, Jürgen W. Gerlach¹, and Stephan Mändl¹ — ¹Leibniz Institute of Surface Modification, Leipzig, Germany — ²Translational Centre for Regenerative Medicine, University of Leipzig, Germany

Plasma immersion ion implantation for inserting nitrogen in transition metals like CoCr alloys or FeCrNi alloys is characterized by near surface ion implantation and a subsequently anomalous high diffusivity leading to nitrogen enriched layers up to several micrometers. At the same time, a lattice expansion of the original fcc structure by 5 to 10% is observed. Preferential trapping with the formation of Cr-N bonds inside the austenitic structure is acclaimed to explain the anomalous concentration profiles at lower temperatures, while beyond 450 °C a transition from the expanded austenite towards CrN precipitates occurs.

In this presentation, photo electron spectra (XPS) are investigated after nitrogen PIII in face-centred-cubic CoCr and FeCrNi alloys in the temperature range from 230 - 580 °C. The process was carried out at pulse voltages of -10 kV, a base pressure of 0.5 Pa and process time of two hours. For FeCrNi alloys, evidence of the nitrogen insertion is only found for the Cr2p peak, however independent of the process temperature, with no changes in the Fe2p and Ni2p core level spectra. For CoCr alloys, despite similar nitrogen concentrations of 30 to 35 at.%, no variation in either Co2p, Cr2p, Fe2p or Ni2p spectra was observed.