Correlation between the atomic configurations and the amorphous-to-icosahedral phase transition in metallic glasses
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ijie Yana) School of Materials Science and Engineering, North Minzu University, Yinchuan 750021, People’s Republic of China; and School of Materials Science and Engineering, North University of China, Taiyuan 030051, People’s Republic of China
Yong Hu School of Materials Science and Engineering, Taiyuan University of Science and Technology, Taiyuan 030024, People’s Republic of China
Zhi Wang School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, China
Sergey V. Ketov Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Leoben 8700, Austria
Jürgen Eckertb) Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Leoben 8700, Austria; and Department of Materials Physics, Montanuniversität Leoben, Leoben 8700, Austria (Received 2 April 2018; accepted 21 May 2018)
Positron annihilation spectroscopy and differential scanning calorimetry were used to evaluate the changes of the atomic configurations in Zr-based metallic glasses (MGs) due to alloying and plastic deformation. The correlation between the atomic configurations of MGs and the amorphous-to-icosahedral phase transition due to heating was investigated. The results indicate that the free volume frozen in the as-cast Zr60Al15Ni25, Zr65Al7.5Ni10Cu17.5, and Zr65Al7.5Ni10Cu17.5Ag5 MGs substantially decreases in sequence. More excess free volume is introduced in Zr65Al7.5Ni10Cu17.5Ag5 MG due to cold rolling and milling. The annihilation of free volume due to alloying considerably stabilizes the icosahedral structure of MGs, which enhances the nucleation and growth of quasicrystals upon heating. However, the nucleation and growth of quasicrystals are considerably suppressed in Zr65Al7.5Ni10Cu17.5Ag5 MG due to cold rolling and milling, during which the more introduced excess free volume results in substantial destruction of short-range order with 5-fold symmetry. The present work further provides direct evidence for the prevalence of icosahedral short-range order in MGs.
I. INTRODUCTION
Since the report on the discovery of the icosahedral phase (I-phase),1 many efforts have been devoted to investigate the formation mechanism of the I-phase, aiming to understand the structure correlation between the pre- and post-transition phases of a supercooled liquid.2,3 However, the required cooling rates of supercooled liquids for precipitation of the I-phase are too high to provide an experimentally accessible time window for Contributing Editor: Jurgen Eckert a) Address all correspondence to this author. e-mail: [email protected] b) This author was an editor of this journal during the review and decision stage. For the JMR policy on review and publication of manuscripts authored by editors, please refer to http://www.mrs. org/editor-manuscripts/. DOI: 10.1557/jmr.2018.187
investigating the nucleation and growth behaviors of the I-phase.4 It has been suggested that the icosahedral shortrange order prevails in metallic glasses (MGs).5–8 The interfacial free energy between the I-phase and th
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