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

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 alpha-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 degrees 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 degrees 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.