Fig. 8. STEM EDS linescan through the particle present in the grain interior. Mainly W is rich within the particle, while content of Fe, Ni and Cu is significantly depleted or absent.
Fig. 9 shows the STEM image of the foil and the EDS map illustrating the composition of particles developed at the grain boundaries and in its neighbourhood. EDS analysis indicates the formation of Cr-rich particles decorating the grain boundary. The area close to the grain boundary is rich in Cr and is heavily depleted in Fe and Ni. In steels having the essential content of Cr, there is a strong tendency to the rapid formation of numerous Cr-rich particles of M23C6 type 29. M23C6 particles nucleate rapidly preferentially at high angle grain boundaries which is in accord with the results of Mazánová et al. 14. Fig. 9 also shows the chains of Cu-rich particles and small-scale Nb-rich particles nucleated at the grain boundary. Cu-rich particles nucleated at the grain boundary are substantially larger than those in the matrix.