Microstructural evolution in near-metatectic Cu–Sn alloys

Microstructures forming in the Cu–Sn system with alloy compositions close to the metatectic composition are characterized. A careful experimental procedure with a variety of holding temperatures and cooling rates allows for unambiguous interpretation of the solidified microstructures. The decay of the high-temperature γ-phase according to the metatectic reaction γ→ε+liquid could not be suppressed even by the highest available quenching rates. Different microstructural features are observed concerning the secondary ε-phase. For low and moderate cooling rates, ε is growing in columnar grains, surrounded by peritectic η-phase. For rapid quenching, secondary ε partially remelts and exhibits fine globulitic particles of η.