Zn38Mg12Ca32Yb18大块金属玻璃的晶化动力学行为

Kinetic Analysis of Crystallization Behaviors in Zn38Mg12Ca32Yb18 Bulk Metallic Glass

摘要:

采用差示扫描量热分析仪,研究了Zn38Mg12Ca32Yb18 大块金属玻璃的在等时和等温状态下的晶化动力学行为。在等时条件下,不同的理论模型来分析特征温度的名义激活能。研究结果表明,采用Kissinger模型,Flynn-Wall-Ozawa 模型和Augis-Bennett模型计算的名义激活能相互吻合。再者,采用Johnson-Mehl-Avrami模型分析了等温过程中晶化转变动力学机。The Avrami 指数 n 的分布区间介于 3.25 到 4.12之间. 我们发现,在等温晶化过程中采用Arrhenius 方程计算得到的激活能比在等时晶化过中采用Kissinger 方程的激活能要大,这可能是由于等温退火过程中能垒比等时晶化过程中的要高所引起的。

Abstract:

The kinetics of crystallization of Zn38Mg12Ca32Yb18 bulk metallic glass was studied by differential scanning calorimetry (DSC) in both non-isothermal and isothermal (at different heating rates) modes. Under isochronal process, theoretical models were adopted to analyze the apparent activation energies for characteristic temperatures. The results indicated that the apparent activation energies for characteristic temperatures in the Zn38Mg12Ca32Yb18 bulk metallic glass by Kissinger model, Flynn-Wall-Ozawa (FWO) model and Augis-Bennett (AB) model were in good agreement with each other. Furthermore, crystallization transformation kinetics during isothermal process was analyzed by the Johnson-Mehl-Avrami (JMA) model. The Avrami exponent n ranges from 3.25 to 4.12 in the isothermal mode. It is noted that the activation energy corresponding to isothermal conditions calculated using Arrhenius equation is larger than the value calculated by the Kissinger method in isochronal conditions, because the energy barrier in isothermal annealing mode is higher than that of isochronal conditions.