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

Abstract

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.