The complex interplay between energetic and kinetic factors that governs the phase and morphology selections can originate at the earliest stage of crystallization in the amorphous parent phases. Because of the extreme difficulties in capturing the microscopic nucleation process, a detailed picture of how initial disordered structures affect the transformation pathway remains unclear. Here, we report the experimental observation of widely varying phase selection and grain size evolution during the devitrification of a homogeneous melt-spun glassy ribbon. Two different crystalline phases $\theta \text{−}{\mathrm{Al}}_5\mathrm{Sm}$ and $\varepsilon \text{−}{\mathrm{Al}}_{60}{\mathrm{Sm}}_{11}$ are found to form in the different regions of the same metallic glass (MG) ribbon during the devitrification. The grain size of the $\varepsilon \text{−}{\mathrm{Al}}_{60}{\mathrm{Sm}}_{11}$ phase shows a strong spatial heterogeneity. The coarse-grained $\varepsilon \text{−}{\mathrm{Al}}_{60}{\mathrm{Sm}}_{11}$ phase coupled with the small volume fraction of the $\theta \text{−}{\mathrm{Al}}_5\mathrm{Sm}$ phase is preferably formed close to the wheel side of the melt-spun ribbon. Combining experimental characterization and computational simulations, we show that phase selection and microstructure evolution can be traced back to different types and populations of atomic clusters that serve as precursors for the nucleation of different crystalline phases. Inhomogeneous cooling rates cause different structure orders across the glass sample during the quenching process. Our findings provide direct insight into the effect of structural order on the crystallization pathways during the devitrification of MG. It also opens an avenue to study the detailed nucleation process at the atomic level using the MG as a platform and suggests the opportunity of microstructure and property design via controlling the cooling process.

中文翻译：

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揭示Al-Sm非晶带材失透过程中的相和形态选择机制

决定相和形态选择的高能和动力学因素之间的复杂相互作用可能起源于非晶态母体相的最早结晶阶段。由于捕获微观成核过程非常困难，因此尚不清楚初始无序结构如何影响转化途径的详细情况。在这里，我们报告的实验观察到，在均匀熔融纺丝玻璃带的失透过程中，相变和晶粒尺寸变化的变化很大。两种不同的结晶相$\theta \text{-}{铝}_{5}m$ 和 $\varepsilon \text{-}{铝}_{60}{m}_{11}$发现在失透过程中在相同的金属玻璃（MG）带的不同区域中形成了α-β。的晶粒尺寸$\varepsilon \text{-}{铝}_{60}{m}_{11}$相显示出强烈的空间异质性。粗粒$\varepsilon \text{-}{铝}_{60}{m}_{11}$ 相与较小的体积分数相结合 $\theta \text{-}{铝}_{5}m$优选在靠近熔纺带的轮侧形成相。结合实验表征和计算模拟，我们显示出相选择和微观结构演变可以追溯到不同类型和数量的原子团簇，它们是不同晶相成核的前兆。在淬火过程中，不均匀的冷却速度会导致整个玻璃样品的结构顺序不同。我们的发现提供了直接的见解，在MG失透过程中，结构顺序对结晶途径的影响。它还为以MG为平台在原子水平上研究详细的成核过程开辟了一条途径，并提出了通过控制冷却过程来进行微观结构和性能设计的机会。