CC483K | CuSn12 | C90800 Bronze

On cooling, α-solid solution precipitates first. The dark edges in the etched microstructure indicate tin segregation in the grains.

The tin-rich remaining melt in the “spandrels” (approx. 16 at% or 26 wt% Sn) finally solidifies eutectically as Cu41Sn11 (light, also in the BSE image) and α-solid solution with approx. 8 at% or 15 wt% Sn (dark).