[en] Carburization experiments with solid carbon source were carried out with austenitic, experimental Fe-Cr-Ni-alloys at 864⁰C/53 h in Ar-atmosphere. The penetrating carbon forms carbides within the matrix, which were investigated by selected area electron diffraction and X-ray analysis. Transmission electron micrographs of extraction replicas and optical metallography revealed the shape, the size and the distribution of the precipitates. Electronbeam microanalysis was used to determine metal contents of some inclusions and to register redistribution of the matrix components. Thermodynamic calculations are compared with the experimental results. At the interface between specimen and carbon source (Fe, Cr)₇C ₃ is formed. The iron content of these carbides was found to be proportional to the iron concentration in the matrix. In addition Cr₃C₂ appeared on the specimen of 15Fe/15Cr/70Ni. The nickel-rich alloys showed a decrease in chromium concentration towards the interface. A similar gradient was found within the grains towards grainboundaries. Alloys 60 and 70Fe/15Cr/Ni carburize along the grain boundaries by relatively thick M₂₃C₆-inclusions. Within the alloys with higher Ni-content (50 and 35Fe/15Cr/Ni) platelike precipitates of M₂₃C₆ and M₂(C,N) dominate, whereas the grain boundaries of 15 Fe/15Cr/70Ni are decorated by M₇C₃-carbides. The precipitates within the grain reach high density within 35 and 15Fe/15Cr/Ni and are almost all of the type Cr₂(C,N) as well as in 50Fe/15Cr/35Ni. The nitrogen content within these carbo-nitrides decreases towards the surface where almost pure Cr₂C might exist. Together with the known carbon contents a discussion of the carburizing mecanisms is added: interface reactions, diffusion of carbide forming elements, solubility of carbon, carbide formation along the grain boundaries and within the grains. (author)