Effects of Be addition on microstructures and mechanical properties of B319.0 alloys

An investigation of iron intermetallics, silicon particles and strengthening precipitates on the microstructures and mechanical properties in B319.0 alloys has been performed. Distinct morphologies were discerned between Be-containing and Be-free alloys at various solution temperatures. Solution treatment was carried out in the temperature range 480°C-530°C for 8 h. Dissolution of the iron intermetallics takes place at temperatures close to 510°C through fragmentation of the phases. The dissolution of iron intermetallics is accelerated with increasing solution temperature. The addition of Be to the alloy will raise the Al-Al₂Cu eutectic melting temperature to 522°C compared with 515°C for Be-free alloys. The Be-free alloys show larger amounts of iron intermetallics than the Be-containing alloys. The addition of Be can change the platelet-like shape of iron intermetallic phases to a comparatively harmless Chinese-script shape. Also, the amount of iron-bearing phases and silicon particles are lower and silicon particles are smaller and more spherical in the Be-containing alloys. Small amounts of Be in B319.0 alloys can also increase the precipitation kinetics of strengthening precipitates. Tensile properties could be improved with optimal solution treatment and the addition of Be.