摘要
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）,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.
基金
supported by National Key Basic Research Program (2007CB613706)
the National Science and Technology Supporting Plan of the Twelfth Five-year (2011BAE22B04-2)
the project of Innovation Project for Talents (PHR200906101)
