Stable icosahedral phase in Mg44 Zn44 Gd12 alloy
The microstructure of the as-cast Mg44Zn44Gd 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 Mg44Zn44Gd12 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 Mg7Zn3 phase. Microstructures of icosahedral phase (I-phase), W-phase and Mg7Zn3 phase in Mg44Zn44Gd12 alloy were investigated. The results indicated that the I-phase in Mg44Zn44Gd 12 alloy was a face-centered icosahedral quasicrystal with stoichiometric composition of Mg42Zn50Gd8 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 Mg7Zn3 phase and W-phase from icosahedral phases. © 2012 The Chinese Society of Rare Earths.
Duke Scholars
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Published In
DOI
ISSN
Publication Date
Volume
Issue
Start / End Page
Related Subject Headings
- Materials
- 0914 Resources Engineering and Extractive Metallurgy