The microstructure of a tool steel usually consists of small, undissolved carbides in a matrix of tempered martensite. The undissolved carbides are relatively small and magnifications of at least 1000X must be used to resolve the individual carbides. Thus, the individual carbides can be seen as small, white (unetched) areas in Figure 3 at 1000X.
Figures 4 through 8 are additional SEM micrographs of the microstructure. Some of the small carbides can be seen quite clearly in Figure 8.