Effects of Er Additions on the Microstructure, Mechanical Properties, and Electrical Conductivity of the Al‐0.4Fe‐0.05Si Alloy

Abstract

The effects of Er addition to the Al‐Fe‐Si alloy on phase composition, microstructure, electrical conductivity, and mechanical properties are studied. Formation of the Al3Fe, Al6Fe, Al3Er, ErSi and Al10Fe2Er intermetallic phases in the Al‐Fe‐Si‐Er alloy is proved by optical microscope (OM), scanning electron microscope (SEM), and transmission electron microscope (TEM). The results show that the spherical Al3Er precipitates with a radius of less than 6.5 nm ± 0.5 nm form a coherent phase boundary with α‐Al. The recovery temperature range and the recrystallization temperature of Al‐Fe‐Si alloy with Er addition after 80% cold deformation is recorded by differential scanning calorimetry (DSC). After annealing at 260 °C for 1 h, the electrical conductivity of the rolled Al‐0.4Fe‐0.05Si‐0.2Er alloy increases from 60.1 to 62.2 IACS%, and the hardness decreases from 50.5 to 36.6 HV. The average tensile properties of the Al‐0.4Fe‐0.05Si‐0.2Er alloy are YS = 131 ± 3 Mpa and ultimate tensile strength (UTS) = 142 ± 3 MPa with 13 ± 1% elongation after annealing at 260 °C for 1 h. The average radius of Al3Er precipitates in Al‐0.4Fe‐0.05Si‐0.2Er is 7.8 ± 0.2 nm, and its strengthening mechanism is Orowan mechanism.