Mg70.8Zn28Nd1.2（mole fraction） alloy containing icosahedral quasicrystal phase （I-phase） was prepared under conventional metal casting conditions. The microstructure, phase constitution and phase structure of the ...Mg70.8Zn28Nd1.2（mole fraction） alloy containing icosahedral quasicrystal phase （I-phase） was prepared under conventional metal casting conditions. The microstructure, phase constitution and phase structure of the alloy were investigated by means of scanning electron microscopy （SEM）, X-ray diffraction （XRD）, energy dispersive spectrometer （EDS） and transmission electron microscopy （TEM）. The resuits showed that the spherical phase in Mg70.8Zn28Nd1.2 alloy was a simple icosahedral quasicrystal with stoichiometric composition of Mg40Zn55Nd5 and quasi-lattice of 0.525 nm. In this research, the as-cast microstructure of Mg70.8Zn28Nd1.2 alloy mainly consisted of Mg40Zn55Nd5 icosahedral quasicrystal phase and Mg7Zn3 columnar crystal matrix. In the growing process of Mg40Zn55Nd5 icosahedral quasicrystal phase, the growth morphology mainly depended on interface energy, adsorption effect of Nd and cooling rate.展开更多
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 micro...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.展开更多
基金supported by National Natural Science Foundation of China (50571073)Natural Science Foundation of Shanxi Province (2009011028-3,2007011067,20051052)High-School Student Project of Taiyuan City (07010713)
文摘Mg70.8Zn28Nd1.2（mole fraction） alloy containing icosahedral quasicrystal phase （I-phase） was prepared under conventional metal casting conditions. The microstructure, phase constitution and phase structure of the alloy were investigated by means of scanning electron microscopy （SEM）, X-ray diffraction （XRD）, energy dispersive spectrometer （EDS） and transmission electron microscopy （TEM）. The resuits showed that the spherical phase in Mg70.8Zn28Nd1.2 alloy was a simple icosahedral quasicrystal with stoichiometric composition of Mg40Zn55Nd5 and quasi-lattice of 0.525 nm. In this research, the as-cast microstructure of Mg70.8Zn28Nd1.2 alloy mainly consisted of Mg40Zn55Nd5 icosahedral quasicrystal phase and Mg7Zn3 columnar crystal matrix. In the growing process of Mg40Zn55Nd5 icosahedral quasicrystal phase, the growth morphology mainly depended on interface energy, adsorption effect of Nd and cooling rate.
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)
文摘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.
