Composition: Cu-4%Sn.

Processing: Sand casting and annealed (700ºC - 2 hours).

Etching: 1 min FeCl₃ alcoholic solution.

Annealing at 700ºC brings the alloy to the α field. At this temperature, diffusion occurs by a vacancy mechanism and the δ dissolves (this phase was formed during casting due to Sn segregation caused by its limited diffusion in Cu). As a result, the applied heat treatment produces a polycrystalline microstructure with equiaxial α grains (FCC). At high magnification is still possible to see some Sn segregation and microporosity. The latter is due to volume contraction during solidification.

Cu-Sn diagram

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