Papers by Keyword: Al₃Er

Abstract: A novel Al-Er master alloy has been prepared through in situ metallothermic reactions of NaErF₄ and aluminium melts. The compound NaErF₄ is formed as a result of the interaction of NaF and ErF₃ in the melt medium KCl. The metallothermic reactions produce erbium, which through low solubility in molten aluminium and forms intermetallic compound Al₃Er. The microstructures of the Al-Er master alloy with different contents of the alloying metal has been investigated. The results showed that the Al-Er master alloy mainly consisted of phases of α-Al and Al₃Er, that confirmed by the results of X-ray diffraction. Backscattered electron imaging of the Al-Er master alloy under a scanning electron microscope (SEM) revealed the presence of phase Al₃Er, which crystallized in the eutectic composition [Al+Al₃Er]. The observed microstructure is explained according to the eutectic reaction in an Al-Er phase diagram. The preparation of Al-Er master alloy by the metallothermic reduction method will allow to reduce energy consumption for master alloy production and to reduce the cost of aluminium alloys alloyed with Er through the novel master alloy.

Abstract: The behaviors of trace element Er on binary Al-Mg and ternary Al-Mg-Mn alloys have been investigated through optical microscopy, x-ray diffraction, scanning electron microscopy with energy dispersive spectroscopy and transmission electron microscope. It was found that Er additions more than 0.4% (wt%) produced a remarkable refinement in grain size of Al-Mg and Al-Mg-Mn alloys castings. Er can enhance the tensile strength of the two group experimental alloys significantly but not greatly decrease the elongation due to the formation of many fine like spherical and dispersive primary and precipitation Al3Er particles during casting and heating process. Al3Er particles have L12 crystal structure (space group Pm3m) with a lattice parameter of 0.42119nm, and have a coherent relationship with the matrix phase α-Al (mismatch only 4.1%), which can be acted as the heterogeneous nucleus during solidification to increase the rate of nucleation, and the other hands it can strongly pin up dislocations and subgrain boundaries and retard the recrystallization of alloys.

Abstract: We have systemically studied the effect of the erbium on the microstructure and the mechanical properties in the 5xxx series aluminum alloys by using optical microscope, transmission electron microscope (TEM) and by tensile testing. The results demonstrate that the tensile strength increased quickly at the beginning of small contents of 0.1%Er both in the hot and cold rolled states, then slowly increased with increasing the contents of Er until 0.4%, at which the best balance of the strength and ductility (438MPa and 9.6%) were obtained. Microstructure observation in the hot rolled state was indicated that the grain structure in the Er free Al-5Mg alloy revealed fully recrystallized grain structure, while in the Al-5Mg containing Er was demonstrated deformation structure, indicating the Er addition delayed the recrystallization behavior by the formation of the precipitation of the Al3Er, which confirmed by means of the X-ray diffraction analysis. Furthermore in the TEM microstructure observation the precipitation of Al3Er was distributed both in the grain interior and subgrain or grain boundaries, which could be pinning the subgrain or grain boundary migration and dislocation movement as well. Consequently the beginning of the recrystallization temperature in the Al-5Mg containing Er was elevated about 50°C than in Al-5Mg without Er. This could be explained that the strength increased without the deterioration of the ductility was attributed to the microstructure refinement by the Er addition.