Effect of High Erbium on Mechanical Properties of Aluminium Alloy

The effects of the addition of the rare earth element, erbium (Er), on the microstructure and mechanical properties of LM 24 alloy were investigated. A microstructural characterisation was performed using an optical microscope (OM) and scanning electron microscope (SEM). When 1.0 wt % of Er was added to LM 24 alloy, the mean area decreased from 1026.16 µm 2 to 95.35 µm 2 , while the aspect ratio decreased from 3.6329 to 2.322. Observations via an optical microscope showed that the unmodified alloy had a coarse plate-like structure. The addition of 1.0 wt % of Er produced the best modification effect on the Si phases, which were transformed into fine particles and short rods. The mechanical properties with various concentrations of Er were investigated by means of an ultimate tensile test and Vicker's hardness test. The results of the ultimate tensile test showed that the elongation increased with an increase in the Er content of up to 0.3 wt %, and then decreased with the addition of more Er. Furthermore, the hardness increased slightly with the addition of Er.