Composition: Cu-42%Zn.

Processing: Sand casting.

Etching: 30 s immersion in FeCl₃ alcoholic solution.

Columnar grains surrounded by equiaxial grains are revealed in the macrostructure. Grains are of β phase and are the first ones to solidify from the molten alloy (see phase diagram). These grains show a substructure consisting of precipitates of α phase (higher Cu content). The latter phase nucleates in regions of high energy, such as grain boundaries, and grows in specific planes of the β matrix, resulting in a Widmanstätten-type structure, where α crystals appear as needles of variable thickness. In the micrographs it can be seen that the β appears darker, whereas the protruding α phase is white.

Cu-Zn diagram

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.