Kang Dong-Hee, Zhang Hao, Yoo Hanbyeol, Lee Hyun Hwi, Lee Sooheyong, Lee Geun Woo, Lou Hongbo, Wang Xiaodong, Cao Qingping, Zhang Dongxian, Jiang Jianzhong
1] Division of Physical Metrology, Korea Research Institute of Standards and Science, Daejeon 305-340, Republic of Korea [2].
1] International Center for New-Structured Materials (ICNSM), and State Key Laboratory of Silicon Materials, Zhejiang University and Laboratory of New-Structured Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China [2] Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, T6G 2V4, Canada [3].
Sci Rep. 2014 Jun 4;4:5167. doi: 10.1038/srep05167.
Glass is a freezing phase of a deeply supercooled liquid. Despite its simple definition, the origin of glass forming ability (GFA) is still ambiguous, even for binary Cu-Zr alloys. Here, we directly study the stability of the supercooled Cu-Zr liquids where we find that Cu64Zr36 at a supercooled temperature shows deeper undercoolability and longer persistence than other neighbouring compositions with an equivalent driving Gibbs free energy. This observation implies that the GFA of the Cu-Zr alloys is significantly affected by crystal-liquid interfacial free energy. In particular, the crystal-liquid interfacial free energy of Cu64Zr36 in our measurement was higher than that of other neighbouring liquids and, coincidently a molecular dynamics simulation reveals a larger glass-glass interfacial energy value at this composition, which reflects more distinct configuration difference between liquid and crystal phase. The present results demonstrate that the higher crystal-liquid interfacial free energy is a prerequisite of good GFA of the Cu-Zr alloys.
玻璃是深度过冷液体的一种凝固相。尽管其定义简单，但玻璃形成能力（GFA）的起源仍然不明确，即使对于二元铜锆合金也是如此。在这里，我们直接研究过冷铜锆液体的稳定性，发现过冷温度下的Cu64Zr36比具有等效驱动吉布斯自由能的其他相邻成分表现出更深的过冷度和更长的持久性。这一观察结果表明，铜锆合金的玻璃形成能力受到晶体-液体界面自由能的显著影响。特别是，我们测量中Cu64Zr36的晶体-液体界面自由能高于其他相邻液体，巧合的是，分子动力学模拟显示该成分下的玻璃-玻璃界面能值更大，这反映了液相和晶相之间更明显的构型差异。目前的结果表明，较高的晶体-液体界面自由能是铜锆合金具有良好玻璃形成能力的先决条件。
