Microstructure and kinetics of Cu/Y ₂O ₃-doped MgB ₂

Cu/Y ₂O ₃-doped MgB ₂ samples with different Y ₂O ₃ content were prepared by traditional solid-state sintering method. The microstructure and phase composition of the material were analyzed by SEM and X-ray diffraction. The results show that layered structure only appeares in Cu/5%Y ₂O ₃-doped sample. The solid-solid reaction of this system is further investigated by kinetics analysis in terms of thermal analysis curves. Finally, the most appropriate mechanism function is ascertained to be Avrami-Erofeev, n=2, which means random nucleation followed by instantaneous growth of nuclei. The activation energy (E) and the pre-exponential factor (A) both trend to be stable at early stage and decrease at final stage.