The use of PEELS for the study of precipitate complexes in HSLA steels

Precipitate complexes in three high strength low alloy (HSLA) Ti-Nb steels have been analysed by parallel electron energy loss spectroscopy (PEELS). The complexes consist of a core with overgrowths of a cap phase. The N:Ti atomic ratios in the three steels are 3.1, 1.7 and 0.77 while the Nb:Ti ratios are 1.5, 0.8 and 0.4 respectively. In each steel, the Nb:Ti ratio in the core is ~0.1 while the N/(Ti+Nb) ratio matches the mean value. The cap composition varies from Nb(C_0.7N_0.3) to NbC to (Nb_0.7Ti_0.3)C_w (with w undetermined) as the N content is reduced.