Effect of Ca on crystallization of Mg-based master alloy containing spherical quasicrystal

• Published in: Transactions of Nonferrous Metals Society of China Vol. 17; no. 2; pp. 273 - 279
• Main Author: 张金山 杜宏伟 卢斌峰 张焱 梁伟 许春香 陆风雷
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2007; School of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China
• Subjects: crystallization; magnesium alloy; microstructure; spherical quasicrystal; 球形准晶; 结晶化; 镁基中间合金; crystallization; magnesium alloy; microstructure; spherical quasicrystal; Ca
• ISSN: 1003-6326
• DOI: 10.1016/S1003-6326(07)60084-3

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, Mg45Zn50Yn4.5Ca0.5 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%, sphericalI-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 primaryI-phase, the hardness of Mg-Zn-Y-Ca master alloy is reduced. The application of spherical I-phase as particulate reinforced phase provides great opporttmities for the improvement of strength and toughness of magnesium alloys.