2.2.1 Light microscope images
Material condition: M – As manufactured (extrusion), without specified mechanical properties
Images of etched specimen at 100, 200 and 500 times magnification. Single phase brass microstructure with grains aligned in the ED. Some grains etch more than others, this is due to crystallographic orientations. The <100>//ED (compare to EBSD results) seem to etch less compared to other orientations. Lead particles in streaks along the ED.
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.
2.2.2 EBSD/EDS analysis in the SEM
EBSD analysis with 1 µm step size
The material show a microstructure consisting of mainly alpha phase. In this limited area it is difficult to make assumptions about grain sizes, phase fractions and texture.
Specimen surface was parallel with extrusion direction (X=ED). Position ¼ depth. Surface was OP-S-polished.
Grain- and phase boundaries
This material is a single phase brass (alpha-brass).
In this material there are not a lot of low angle boundaries and the twin boundaries look complete and straight. The assumption would be that recrystallisation occurred after extrusion.
EDS mapping in parallel to EBSD analysis
Some segregation of Cu/Zn is seen but almost no Beta phase was found in the microstructure. Pb particles in streaks, the variation between low and high Zn level was about 33-36%. Small Fe particles could be detected as well, but P, As, Bi etc. was not detected which indicates low levels and very small particles if present.
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). The pole figures show that there are actually preferred orientations (or texture), strong <100> and weaker <111> and <110> in ED. Some beta phase was found in streaks, but only VERY little, 0.01%.
Grain size, area weighted distribution