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The microstructure of the as-cast Mg 44 Zn 44 Gd 12 alloy was investigated by using X-ray diffraction(XRD),differentical scanning(DSC),scanning electron microscopy(SEM) and a detailed transmission electron microscope.The XRD,DSC and SEM results indicated that the as-cast Mg 44 Zn 44 Gd 12 alloy were mainly composed of three types of phases:the primary solidification phase,the dendritic phase and the eutectic phase.The primary solidification phase had an icosahedral structure.The dendritic phase was the W-phase,and eutectic structure phase was the Mg 7 Zn 3 phase.Microstructures of icosahedral phase(I-phase),W-phase and Mg 7 Zn 3 phase in Mg 44 Zn 44 Gd 12 alloy were investigated.The results indicated that the I-phase in Mg 44 Zn 44 Gd 12 alloy was a face-centered icosahedral quasicrystal with stoichiometric composition of Mg 42 Zn 50 Gd 8 which had an excellent thermal stability up to 420 °C.The solid solution of the Gd gradually decreased during solidification,which played an important role in activating the formation of Mg 7 Zn 3 phase and W-phase from icosahedral phases.
The microstructure of the as-cast Mg 44 Zn 44 Gd 12 alloy was investigated by using X-ray diffraction (XRD), different scanning (DSC), scanning electron microscopy (SEM) and a detailed transmission electron microscope. SEM results indicated that the as-cast Mg 44 Zn 44 Gd 12 alloy were mainly composed of three types of phases: the primary solidification phase, the dendritic phase and the eutectic phase. The primary solidification phase had an icosahedral structure. The dendritic phase was the W-phase, and eutectic structure phase was the Mg 7 Zn 3 phase. Microstructures of icosahedral phase (I-phase), W-phase and Mg 7 Zn 3 phase in Mg 44 Zn 44 Gd 12 alloy were investigated. The results that the I-phase in Mg 44 Zn 44 Gd 12 alloy was a face-centered icosahedral quasicrystal with stoichiometric composition of Mg 42 Zn 50 Gd 8 which had an excellent thermal stability up to 420 ° C. The solid solution of the Gob gradually during solidification, which played an importa nt role in activating the formation of Mg 7 Zn 3 phase and W-phase from icosahedral phases.