On the detection of MX-precipitates in microalloyed steels using energy-filtering TEM

摘要: The properties of microalloyed steels and HSLA depend predominantly on the size composition nanometre-sized MX precipitates consisting Nb, Ti, V, C N. In this work we present a rapid powerful method for visualizing these small directly in steel matrix. This can be achieved by energy-filtering TEM 200-kV microscope. We have recorded elemental maps (three-window method) jump-ratio images (two-window using inner-shell ionization edges; e.g. Fe-M23, Fe-L23, V-M23, V-L23, Nb-N23, Nb-M45, C-K N-K edges. found that matrix best visualized recording image element. If specimens are thinner than 30 nm high resolution low detection limits essential, energy-loss edges should used preferentially; case Fe-M23 edge instead Fe-L23 edge. with edge, about 2 diameter may detected. With thicker samples if is not as higher preferable, because diffraction effects less possible. The chemical larger (10 nm) could determined EDX spectra an STEM probe. Nb V atomic ratio 3, but detect carbon or nitrogen spectra. distribution including both Nb-N23 V-M23 However, it was possible to content unequivocally due overlapping Nb-M45