THE EPSILON-]GAMMA' TRANSFORMATION IN N-IMPLANTED ALPHA-FE

The phase transformations of epsilon-Fe3-xN to gamma'-Fe4N and gamma'-Fe4N to alpha-Fe were studied in nitrogen implanted iron. These transformations were studied by the conversion electron Mossbauer spectroscopy (CEMS) technique as a function of time and temperature of annealing of the N-implanted samples. The epsilon phase was formed in the alpha-Fe sample implanted with 4 x 10(17) N/cm2 by subsequent 1 hour annealing at temperatures of 200-degrees-C, 250-degrees-C and 300-degrees-C. The samples were then systematically annealed at 300-degrees-C, 350-degrees-C and 400-degrees-C for increasing periods of time in order to follow the decomposition of epsilon and gamma' phases. The detailed analysis of the decomposition rates of these phases allowed the calculation of the activation energies for both transformations as 0.8 eV and 1.3 eV for epsilon --> gamma' and gamma' --> alpha transformations, respectively.