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Stable icosahedral phase in Mg_(44)Zn_(44)Gd_(12) alloy
Ist Teil von
中国稀土学报:英文版, 2012, Vol.30 (5), p.503-506
Erscheinungsjahr
2012
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
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.