Effect of cooling rates on solidification and microstructure of rapidly solidified Mg57Zn37Y6 quasicrystal alloy. Issue 21 (28th September 2015)

• Record Type: Journal Article
• Authors: Xu, Min; Teng, Xinying; Geng, Jiwei
• Is Part Of: Journal of materials research. Volume 30:Issue 21(2015)
• Page Start: 3324
• Page End: 3330
• Publication Date: 2015-09-28
• Subjects: Mg57Zn37Y6 alloys, -- quasicrystals, -- cooling rate, -- rapid solidification, -- phase transition; Materials -- Research -- Periodicals; 620.1105
• DOI: 10.1557/jmr.2015.283
• Languages: English
• ISSNs: 0884-2914

Abstract

Abstract: Abstract : The influence of cooling rates on the solidification and microstructure of rapidly solidified quasicrystal alloys with a nominal compositions of Mg57 Zn37 Y6 (at.%) prepared by melt spinning method 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, and transmission electron microscopy. The results show that rapid solidification refines and homogenizes the microstructure of Mg57 Zn37 Y6 alloys, compared to the conventionally-cast master alloy. With the increasing cooling rate of rapid solidification, the thickness of the ribbon decreases greatly and a larger amount of I-phase can be formed. α-Mg, MgZn, and icosahedral phases are found in the as-cast alloy, but the MgZn phase is absent from rapidly solidified alloys. The I-phase in both as-cast and rapidly solidified alloys can precipitate directly from the melt during the solidification process. A higher cooling rate can lead to a large degree of supercooling, resulting in a decreased phase transition temperature and a large number of icosahedral short-range orders (ISROs). ISROs can act as templates in liquid and promote the nucleation of I-phase.