Braunite in gas nitrided sintered iron

The formation of the eutectoid of the Fe-N system, braunite, was investigat ed in gas nitrided sintered iron samples in dependence on porosity and the nitriding time. The samples were nitrided in the gas mixture N-2-(5 and 9)% NH3 at 560 degrees C for 1 to 4h and also in pure NH3 and then annealed fo r 1 and 6h in NP The formation of braunite in sintered. components was obse rved after a 2h treatment in the N-2-5NH(3) atmosphere in the core of the s ample with a porosity above of 10%. A decrease in porosity shifted the form ation of the braunite towards the surface in the form of a continuous layer below the epsilon-phase. Braunite has a lamellar or troostite-similar char acter under the given conditions. While being annealed in nitrogen, braunit e dissolves and becomes the source of nitrogen for the broadening of the di ffusion layer.