Effect of Cooling Rates on the Solidification and Microstructure of Rapidly Solidified Mg_70.8Zn₂₈Nd_1.2 Quasicrystal Alloy

Abstract:

The influence of cooling rates on the solidification and microstructure of rapidly solidified quasicrystal alloy Mg_70.8Zn₂₈Nd_1.2(at.%) was investigated. The microstructure, phase constitution, phase transition and phase structure of the alloys were examined by means of scanning electron microscopy, x-ray diffraction, energy dispersive spectrometer, differential scanning calorimetry. The experimental results showed that the phase composition of as-cast Mg_70.8Zn₂₈Nd_1.2 alloy includes quasicrystal I-phase and Mg₇Zn₃ phase. For the rapidly solidified alloy ribbons, when the speed is not higher than 400 r/min, the microstructure includes I-phase, Mg₇Zn₃ phase and α-Mg phase. When the speed is at the range of 400-2000r/min, the Mg₇Zn₃ phase disappears and only quasicrystal with α-Mg phase exist. With the increase of cooling rate, the grain size decreases and there are a large number of microcrystals in the microstructure. When the speed reaches higher than 2500 r/min, amorphous phase appeared. Differential thermal analysis showed that quasicrystal exist at about 340°C.

• Periodical: Materials Science Forum (Volume 898)
• Pages: 246-253
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.898.246
• Online since: June 2017
• Authors: Xing Jing Ge, Xin Ying Teng*, Shu Min Xu, Jin Yang Zhang
• Keywords: Amorphous, Cooling Rate, Mg_70.8Zn₂₈Nd_1.2 Quasicrystal

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