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Multistep Crystallization and Melting Pathways in the Free-Energy Landscape of a Au-Si Eutectic Alloy.
Advanced Science ( IF 14.3 ) Pub Date : 2020-05-14 , DOI: 10.1002/advs.201903544 Güven Kurtuldu 1 , Jörg F Löffler 1
Advanced Science ( IF 14.3 ) Pub Date : 2020-05-14 , DOI: 10.1002/advs.201903544 Güven Kurtuldu 1 , Jörg F Löffler 1
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Crystals do eventually melt if they are heated to their characteristic melting point. However, this is practically only the case for high‐temperature stable crystals, whereas low‐temperature metastable crystals generally transform, before melting, into a more stable solid during heating. Here, it is illustrated that low‐temperature crystals can, however, be melted via fast differential scanning calorimetry (FDSC), even in metallic systems where nucleation and growth kinetics are rapid. For a Au–Si eutectic alloy, various metastable and stable solid states, i.e., (Au–α), (Au–β), γ, and (Au–Si), which form under well‐controlled conditions and melt at high heating rates by preventing the metastable‐to‐stable solid phase transition, are isolated. It is demonstrated that Au81.4Si18.6 can fully melt at various temperatures, i.e., 294 °C, 312 °C, 352 °C, and 363 °C, with differing melting enthalpies ranging from 6.52 to 9.83 kJ mol−1. The melting and crystallization paths of the metastable solids are determined by constructing an energy−temperature diagram. This approach advances the general understanding of nucleation in metallic and other systems, and is expected to contribute to the detailed understanding of thermophysical phenomena that occur at spatially reduced dimensions and/or short time scales, for example in thin‐film deposition, nanomaterials production, or additive manufacturing.
中文翻译：
Au-Si 共晶合金自由能景观中的多步结晶和熔化路径。
如果晶体被加热到其特征熔点，那么它们最终会熔化。然而，这实际上仅适用于高温稳定晶体，而低温亚稳晶体通常在熔化前在加热过程中转变为更稳定的固体。然而，这里表明，即使在成核和生长动力学快速的金属系统中，低温晶体也可以通过快速差示扫描量热法（FDSC）熔化。对于Au-Si共晶合金，各种亚稳态和稳定的固态，即(Au-α)、(Au-β)、γ和(Au-Si)，在良好控制的条件下形成并在高温下熔化通过防止亚稳态到稳定固相转变的速率被分离出来。结果表明，Au 81.4 Si 18.6在294 ℃、312 ℃、352 ℃和363 ℃等不同温度下均可完全熔化，熔化热函范围为6.52至9.83 kJ mol -1 。亚稳态固体的熔化和结晶路径是通过构建能量-温度图来确定的。这种方法增进了对金属和其他系统中成核的一般理解，并有望有助于详细理解在空间减小的维度和/或短时间尺度上发生的热物理现象，例如在薄膜沉积、纳米材料生产、或增材制造。
更新日期：2020-06-24
中文翻译：
Au-Si 共晶合金自由能景观中的多步结晶和熔化路径。
如果晶体被加热到其特征熔点，那么它们最终会熔化。然而，这实际上仅适用于高温稳定晶体，而低温亚稳晶体通常在熔化前在加热过程中转变为更稳定的固体。然而，这里表明，即使在成核和生长动力学快速的金属系统中，低温晶体也可以通过快速差示扫描量热法（FDSC）熔化。对于Au-Si共晶合金，各种亚稳态和稳定的固态，即(Au-α)、(Au-β)、γ和(Au-Si)，在良好控制的条件下形成并在高温下熔化通过防止亚稳态到稳定固相转变的速率被分离出来。结果表明，Au 81.4 Si 18.6在294 ℃、312 ℃、352 ℃和363 ℃等不同温度下均可完全熔化，熔化热函范围为6.52至9.83 kJ mol -1 。亚稳态固体的熔化和结晶路径是通过构建能量-温度图来确定的。这种方法增进了对金属和其他系统中成核的一般理解，并有望有助于详细理解在空间减小的维度和/或短时间尺度上发生的热物理现象，例如在薄膜沉积、纳米材料生产、或增材制造。
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