In-situ probing of metallic glass formation and crystallization upon heating and cooling via fast differential scanning calorimetry
In-situ probing of metallic glass formation and crystallization upon heating and cooling via fast differential scanning calorimetry
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DOI：
10.1063/1.4884940
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发表时间：
2014-06-23
影响因子：
4
通讯作者：
Loeffler, J. F.
中科院分区：
文献类型：
--
作者：
Pogatscher, S.;Uggowitzer, P. J.;Loeffler, J. F.
采用快速差示扫描量热法研究了小尺度金基金属玻璃样品的晶化过程。快速冷却和加热使得可以原位探测从过冷液态的玻璃形成或从玻璃态到平衡液体的直接转变，从而确定用于结晶的临界冷却（Phi（c）类似于600 Ks（-1））和加热速率（Phi（h）类似于6 × 10（3）Ks（-1））。采用线性加热和等温量热法研究了整个过冷液相区的结晶动力学。我们表明，晶体生长的温度依赖性反映在Au49Ag5.5Pd2.3Cu26.9Si16.3的“基辛格图”中，并且与玻璃体系中晶体生长的模型相当。线性加热和加热后的等温测量表明，它的结晶总是生长控制的熔化温度。相反，对于从平衡液体的低程度的直接过冷，等温结晶是成核控制的，而在大的过冷度，它再次生长控制。金属玻璃的整体结晶行为呈现在冷却时的完整时间-温度-转变图中，并且迄今为止无法访问各种冷却程序后的加热。(C)2014 AIP Publishing LLC.
The crystallization of small-scale Au-based metallic glass samples was investigated by fast differential scanning calorimetry. Rapid cooling and heating makes possible in-situ probing of glass formation from the supercooled liquid state or direct transition from the glassy state to the equilibrium liquid and, thereby, the determination of a critical cooling (Phi(c) similar to 600 Ks(-1)) and heating rate (Phi(h) similar to 6 x 10(3) Ks(-1)) for crystallization. Crystallization kinetics was studied in the whole supercooled liquid region by linear heating and isothermal calorimetry. We show that the temperature dependence of crystal growth is reflected in a "Kissinger plot" for Au49Ag5.5Pd2.3Cu26.9Si16.3 and compares well with a model for crystal growth in a glassy system. Linear heating and isothermal measurements after heating the glass show that its crystallization is always growth-controlled up to its temperature of melting. In contrast, for a low degree of direct undercooling from the equilibrium liquid isothermal crystallization is nucleation-controlled, whereas it is again growth-controlled at large undercooling. The overall crystallization behavior of the metallic glass is presented in a complete time-temperature-transformation map on cooling and, so far not accessible, on heating after various cooling procedures. (C) 2014 AIP Publishing LLC.