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首页> 外文期刊>Journal of Non-Crystalline Solids: A Journal Devoted to Oxide, Halide, Chalcogenide and Metallic Glasses, Amorphous Semiconductors, Non-Crystalline Films, Glass-Ceramics and Glassy Composites >Estimation of diffusivity governing primary nanocrystallisation and its relation to thermal stability of amorphous phases
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Estimation of diffusivity governing primary nanocrystallisation and its relation to thermal stability of amorphous phases

机译：控制一次纳米结晶的扩散率及其与非晶相热稳定性的关系

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摘要

Thermal stability and changes of both the average size of Al nanocrystals and their crystallised volume fraction formed in a series of the amorphous Al-(Ni,Co,Fe)-(Gd,Y,Tb) alloys as well as of α-Fe(Si) in the Fe _(73.5)Si _(13.5)B _(9)Cu _(1)Nb _(3) alloy under isothermal conditions have been experimentally studied by a combination of X-ray diffraction (XRD) analysis, differential scanning calorimetry (DSC) and electrical resistance measurements. The experimental data have been fitted with the analytical models describing the diffusion-limited growth of nanocrystals and nanocrystallisation kinetics accounting for impingement of diffusion fields and the values of the effective diffusivity governing this process have been estimated. The obtained values of the diffusivity in Al-based amorphous alloys follow the Arrhenius-type dependencies with correlation between the pre-exponential factors and the activation energies somewhat different from that found for impurity diffusion coefficients in amorphous alloys. It has been established that at the onset crystallisation temperatures varying from 453 to 778 K, the values of the effective diffusivity in the investigated amorphous alloys are in the narrow range of 1.7-4.7 × 10 ~(- 20) m ~2 s ~(- 1), which indicates a crucial role of the effective diffusivity for the thermal stability of nanocrystals forming amorphous alloys and the possible reason for this is discussed.
机译：在一系列非晶Al-（Ni，Co，Fe）-（Gd，Y，Tb）合金以及α-Fe（）中形成的Al纳米晶体的热稳定性和平均尺寸及其结晶体积分数的变化通过X射线衍射（XRD）分析，对Fe_（73.5）Si _（13.5）B _（9）Cu _（1）Nb _（3）合金在等温条件下的Si）进行了实验研究，差示扫描量热法（DSC）和电阻测量。实验数据已经与分析模型相吻合，描述了限制扩散的纳米晶体的生长和解释扩散场影响的纳米结晶动力学，并估算了控制该过程的有效扩散率值。在铝基非晶合金中获得的扩散率值遵循Arrhenius型依赖关系，预指数因子与活化能之间的相关性与在非晶合金中杂质扩散系数所发现的有些不同。已经确定，在开始结晶温度为453至778 K时，所研究的非晶态合金中的有效扩散系数值在1.7-4.7×10〜（-20）m〜2 s〜（ -1），这表明有效扩散率对形成非晶态合金的纳米晶体的热稳定性起着至关重要的作用，并讨论了可能的原因。

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