Abstract: The microstructures and mechanical properties of the rolled AZ61 alloys containing different contents of Y (0, 0.5, 0.9, 1.4%Y respectively) were studied. Phase analysis was performed by X-ray diffraction(XRD). Microstructures of experimental materials were observed by optical microscope(OM) and scanning electron microscope(SEM) equipped with energy dispersive spectrometer(EDS). The results show that the alloys with variable Y contents all contain a second-phase Al₂Y. The amount of Al₂Y increases with the increasing of Y content while that of Mg₁₇Al₁₂ decreases. Moreover, Y refines the microstructures of as-cast and rolled alloys. The finest average grain size is obtained in the alloy containing 0.9%Y with the best mechanical properties. When the Y content is up to 1.4%, Al₂Y phase in the alloy coarsens, which leads to the drop of tensile strength.

Key words: AZ61 alloy; rare earth; yttrium; hot rolling; microstructure; mechanical properties