Liquid-liquid transition in a strong bulk metallic glass-forming liquid
Liquid-liquid transition in a strong bulk metallic glass-forming liquid
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DOI：
10.1038/ncomms3083
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发表时间：
2013-07-01
影响因子：
16.6
通讯作者：
Busch, Ralf
中科院分区：
文献类型：
--
作者：
Wei, Shuai;Yang, Fan;Busch, Ralf
多晶型相变在结晶固体中很常见。最近的研究表明，具有不同熵和结构的两种液体形式之间也可能存在相变。这种液-液转变已在多种物质中进行了研究，包括水、Al2O3-Y2O3 和网络玻璃形成剂。然而，由于避免结晶和/或在高温/压力下测量的实验困难，液-液转变的性质存在争议。在这里，我们报告了以非（或弱）方向键为特征的块体金属玻璃形成体系 Zr41.2Ti13.8Cu12.5Ni10Be22.5 中温度诱导的弱一级液-液转变的热力学和结构证据。我们的实验结果表明，转变过程中的局部结构变化引起了剧烈的粘度变化，而没有检测到密度异常。这些变化与液体中的最大热容相关。我们的研究结果支持这样的假设：液体的“强”动力学（低脆性）可能源于其玻璃化转变之上的潜在 lambda 转变。
Polymorphic phase transitions are common in crystalline solids. Recent studies suggest that phase transitions may also exist between two liquid forms with different entropy and structure. Such a liquid-liquid transition has been investigated in various substances including water, Al2O3-Y2O3 and network glass formers. However, the nature of liquid-liquid transition is debated due to experimental difficulties in avoiding crystallization and/or measuring at high temperatures/pressures. Here we report the thermodynamic and structural evidence of a temperature-induced weak first-order liquid-liquid transition in a bulk metallic glass-forming system Zr41.2Ti13.8Cu12.5Ni10Be22.5 characterized by non- (or weak) directional bonds. Our experimental results suggest that the local structural changes during the transition induce the drastic viscosity changes without a detectable density anomaly. These changes are correlated with a heat capacity maximum in the liquid. Our findings support the hypothesis that the 'strong' kinetics (low fragility) of a liquid may arise from an underlying lambda transition above its glass transition.