Quantitative analysis of a complex metal carbide formed during furnace cooling of cast duplex stainless steel using EELS and EDS in the TEM

摘要

In this work, a method to determine the atomic ratio of Mo and C within complex metal carbides using EELS in the TEM has been developed. The method is based on the determination of k-factors for given experimental conditions from the EEL spectra of Mo_2C and MoO_3 standards, which had been independently checked by XRD and EPMA. Factors affecting the k_(Mo/C) value of the Mo_2C standard were also investigated and the value was shown to be insensitive to background subtraction window width but sensitive to prolonged irradiation and specimen thicknesses above a critical value. The method and k-factor obtained from the Mo_2C standard was applied to spectra from a complex metal carbide precipitate formed during furnace cooling of a cast duplex stainless steel. Using EELS and EDS in the TEM, the composition was estimated to be (Cr_(1.52)Fe_(2.33)Mo_(1.25)Ni_(0.17)Si_(0.46))C, which is close to M_6C stoichiometry, and the structure was confirmed by electron diffraction.