Novel precipitation strengthened Al-Y-Sc-Er alloy with high mechanical properties, ductility and electrical conductivity produced by different thermomechanical treatments

This study investigated the evolution of the microstructure, mechanical properties, and electrical conductivity of novel Al-0.2Y-0.2Sc-0.3Er alloy in as-cast, as-rolled, and annealed states. Aluminum solid solution and τ2 (Al75–76Er11–17Y7–14) eutectic phase particles with a size of 50–200 nm were identified in the as-cast alloy sample by scanning electron microscopy investigation and phase diagram analyses. A precipitation strengthening mechanism was implemented during annealing at 300 °C for 7 h due to L12 precipitates of Al3(Sc,Y,Er) phase with a maximum diameter of 10 nm. The same structure was formed in the samples annealed at 300 °C for 7 h after rolling the as-cast alloy without aging treatment. The samples aged before rolling formed a more homogenous and finer substructure, with a grain structure formed after annealing rolled sheets. Significantly more uniform structures facilitate achieving higher strength and electrical conductivity. Al-0.2Y-0.2Sc-0.3Er alloy aged at 300 °C for 7 h, hot and cold rolled, and annealed at 300 °C for 7 h exhibited a good combination of strength and electrical conductivity: YS = 191 MPa, UTS = 207 MPa, El. = 14 %, and EC = 59.7 % IACS.