Analysis of a plasma nitrided Ti-6Al-4V spur gear surface

The unworn and worn surface of a cold forged and plasma nitrided Ti-6Al-4V gear was analyzed for the distribution of elements, Titanium, aluminum and vanadium distributions were mapped using the micro-PIXE technique, while nitrogen concentration and depth profiles were carried out in the surface region by NRA resonance profiling, and also micro-NRA techniques using the nuclear reaction N-15(p,alpha gamma)C-12. The nitrogen layer thickness was determined as about 17 mu m below the surface, and the concentration at the surface reached the value of up to 16 mass%. Due to plasma nitriding process aluminum and vanadium were found depleted in the first few micrometers from the surface. It was evident that local agglomeration occurred for both elements in the surface layer, This was probably caused by the residual stresses developed during the forging process. (C) 1997 Elsevier Science B.V.