首页|Icosahedral Ordering Induced by Cr in Al-Zn Alloy Liquid
Icosahedral Ordering Induced by Cr in Al-Zn Alloy Liquid
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NSTL
Springer Nature
Cr atoms can promote the formation of icosahedral short-range order (ISRO) in Al-Zn alloy liquid, which is believed to be the structural origin of the quasicrystal (QC) phase in the assumption of a QC-enhanced nucleation mechanism. However, this claim still lacks experimental evidence. In this work, we investigate the liquid structure of Al-Zn and Al-Zn-Cr alloys through high-energy X-ray diffraction at a synchrotron facility. The constrained reverse Monte Carlo simulation method is used to obtain the three-dimensional atomic configuration. The results show that the Cr addition reduces the formation of Al-centered ISRO and increases the formation of Zn-centered ISRO. Large amounts of ISRO or high five-fold symmetry are found around Cr atoms. Furthermore, the correlation between Al and Zn atoms is significantly changed due to the Cr addition. The pentagon-rich Al-centered and Cr-centered clusters show a strong tendency to aggregate and build interpenetrating structures on a medium-range scale. The icosahedral medium-range order (IMRO) will form through the linkage of vertex-, edge-and intercross-shared types of the Cr-centered icosahedra or icosahedra-like clusters. In particular, an IMRO structure with a composition similar to the Al_(45)Cr_7 phase is found, which is considered the intermediate phase of fcc-Al nucleation. These findings may provide structural hints of the QC-enhanced nucleation mechanism.
SAICHAO CAO、LONG ZENG、MINGXU XIA
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School of.Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, P.R. China
NSTL
Springer Nature
