CW617N, round bar, d=24 mm

1.4.1 Light microscope images

Images of etched specimen at 100, 200, 500 and 1000 times magnification. The duplex brass microstructure can be seen with distinct difference in etch response between the two phases. Alpha phase appears bright and beta phase darker. Lead particles are etched dark. Grain boundaries in the beta phase are visible to some extent, but no strong difference between grains. From EBSD we learn that the beta phase has very strong texture in ED which explains why the etching is similar.

Etching: 5g ferric chloride + 10ml conc. hydrochloric acid + 100 ml de-ionised water.

Specimen surface was parallel with extrusion direction (X=ED). Position ¼ depth.

CW617N, 100x Magnification

CW617N, 200x Magnification

CW617N, 500x Magnification

CW617N, 1000x Magnification

Composition of CW617N

1.4.2 EBSD/EDS analysis in the SEM

EBSD analysis with 1 µm step size

The material show a fine grained duplex microstructure consisting of alpha-beta phase, and lead particles. In this limited area it is difficult to make assumptions about texture.

Specimen surface was parallel with extrusion direction (X=ED). Position ¼ depth.

Surface was OP-S-polished.

FSD image of the area for EBSD analysis. Relatively fine and homo-geneously dispersed Pb particles are seen.

IPF-Z EBSD map with colours according to crystal orientations in Z direction (transverse dir.).

EBSD phase map, alpha phase is red and in beta phase is blue. Grain boundaries (>15°) and low angle boundaries (2-15°) are included.

IPF in X direction (extrusion dir.). Grain boundaries (black) and phase boundaries (blue) are included in the image.

Alpha phase crystal orientations (ED)

Beta phase crystal orientations (ED)

Grain- and phase boundaries

In this material there are not a lot of low angle boundaries. The assumption would be that recrystallisation occurred after extrusion.

The beta phase do not contain a lot of grain boundaries at all, this is easier seen in the previous slide.

Phase boundaries are light blue (aqua). Grain boundaries (>15°) are black. Low angle boundaries (2-15°) are thin black. Twin boundaries (60<111>) are red.

EDS mapping in parallel to EBSD analysis

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Large area mapping – Many (>40) analyses stitched together

The large area make statistics for grain size, phase fractions, texture, etc. better and now it is obvious that there ARE preferred orientations in X (ED). Pole figures for both phases show textures for the alpha phase <100>&<111>//ED, and for the beta phase <110> // ED.