Transactions of Nonferrous Metals Society of China
JOURNAL OF RAILWAY SCIENCE AND ENGINEERING
|Vol. 17 No. 2 April 2007|
alloy containing spherical quasicrystal
（School of Materials Science and Engineering, Taiyuan University of Technology,
Taiyuan 030024, China）
Abstract:Spherical icosahedral quasicrystalline phase (I-phase) was obtained by introducing Ca into Mg-Zn-Y alloy under conventional casting conditions. Due to the addition of Ca, Mg45Zn50Y4.5Ca0.5 primary I-phase, which is thermodynamically stable and homogeneously distributed, was generated instead of decahedral quasicrystalline phase during the solidification process; the morphology of primary I-phase in the solidification microstructure changed from petal-like one (60−80 μm) to spherical one (≤15 μm). When the mass fraction of Ca reaches 0.05%, spherical I-phase with the largest quantity, highest spheroidization rate and highest circular degree can be obtained. Meanwhile, due to the changed morphology and the decreased size of primary I-phase, the hardness of Mg-Zn-Y-Ca master alloy is reduced. The application of spherical I-phase as particulate reinforced phase provides great opportunities for the improvement of strength and toughness of magnesium alloys.
Key words: magnesium alloy; Ca; spherical quasicrystal; crystallization; microstructure