The Effects of Impurities on the Phase Composition and the Properties of the Al–Cu–Gd Alloy

The effect of impurities on the phase composition and the properties of a new quasibinary Al–Cu–Gd alloy have been investigated. The microstructure in the cast alloy consists of an aluminum solid solution, a dispersed eutectic with the Al₈Cu₄Gd phase with approximately 1% iron impurity dissolved, and an (AlGdCuSi) phase with an approximate composition of Al₈₀Gd₅Cu₈Si₅. High-temperature homogenization at 600°С results in the fragmentation and spheroidization of the solidification-induced phases, including the silicon-containing phase. The annealing of cold-worked sheets at temperatures up to 250°C results in roughly the same softening associated with the recovery and polygonization processes in alloys with and without impurities. The structure is completely recrystallized after 1-hour annealing at 300°C and has an average grain size of 7.5 μm, which slightly increases to 11 μm after annealing at 550°C. The yield strength of the alloys rolled and annealed at 100–150°С is 227–276 MPa with elongation of 5%. Iron and silicon impurities have no negative effects on the microstructure and mechanical properties of this new alloy.