BS contrast mappings of the five DP steel samples annealed at different temperatures. In contrast to martensite the BS value is higher for ferrite, which appears brighter in the mappings and allows to determine the MVF in the mapped region. In a) only dark gray to black pixels are visible, proving that the scanned area mostly consists of martensite. In b)-e) increasing areas of lighter gray corresponding to the ferrite phase are visible for decreasing annealing temperatures. For e) a magnified view of the BS microstructure is shown.

Contexts in source publication

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... DP steel samples were at first characterized by EBSD to obtain information about the microstructure and the MVF on the same length scale as the subsequent characterization by UHV-EDXS. For EBSD, the BS contrast mappings for the bcc crystal structure of all five samples are shown in Fig. 2. The martensite and ferrite grains of the DP steel can be distinguished by the brightness level of the BS contrast, since the EBSD quality, which is quantified by the BC or BS, is different for the two phases [12][13][14][20][21][22]. The formation of martensite results in a large number of dislocations and high residual strain leading ...

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... has a higher BS value and a brighter colour than martensite in the mappings, which was used to determine the MVF of the sample material [13,14,[20][21][22]. For the considered set of samples, the MVF decreases with decreasing annealing temperature and larger areas with grains of ferrite are formed, as shown in the inset and the magnified view of Fig. 2 ...

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... Mn show a rather uniform distribution, beside minor Mn segregations in form of stripes within the scanned area. C is also homogeneously distributed in the mapping of Fig. 3 a) for the sample, which consist only of martensite. In contrast, an inhomogeneous distribution of C is observed for the mappings depicted in Fig. 3 b)-e). A comparison with Fig. 2 shows that this distribution ressembles the one of martensite, with the martensite being brighter in colour in the C mapping and darker in colour in the BS mapping. To ensure that the C concentration differences do not originate from channeling effects of differently oriented grains, the measurements were repeated for one of the ...

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... images give no clear indication whether the grains are martensite or ferrite ones. Nevertheless, it can be observed that some indents are significantly smaller than others. Since martensite is expected to be harder than ferrite the indentations should be shallower for martensite. By directly comparing the electron images with the BS images (see Fig. 2) it is possible to identify whether the tested grain is of martensite or ferrite type and by additionally evaluating the EDXS spectrum a correlation between the C-content of the martensite and the hardness can be obtained. In Fig. 7 e) such a direct comparison between the three mapping types for a small area is depicted as an example. ...