【摘要】 采用旋铸急冷工艺在大气环境中制备出了Co77.5Si13.5B9非晶合金带材。X射线衍射(XRD)和透射电镜(TEM)分析表明样品为完全非晶。用差热分析仪测量了非晶薄带的热稳定性参数Tg,Txi,Tpi,加热速度分别为5,10,15,35,55,75,95 K.min-1。分析了合金的非等温晶化动力学行为,计算了两个析晶峰的晶化表观激活能。研究发现:不同升温速率的DTA曲线表明非晶合金的晶化过程为两步晶化,在连续加热条件下,随升温速率的加快,Co77.5Si13.5B9非晶合金的特征温度Tg,Txi,Tpi均向高温区移动,说明其玻璃转变和晶化行为均有动力学效应。当分别采用晶化开始温度和两个峰值温度时,所得非晶合金的激活能并不是一稳定值。Ozawa方法计算出的激活能值与Kissinger法计算出的结果是一致的。非晶态Co77.5Si13.5B9合金的晶化百分比与退火温度和退火时间的关系曲线均呈S型曲线,随加热速度的增加,非晶合金的晶化百分比与温度的关系曲线向高温处移动,晶化百分比与时间的关系曲线则向时间缩短的方向移动。更多还原

【Abstract】 The investigation on Co-based amorphous alloys was a foreland of condensation physics and for design of new materials with uniformly physical and chemical properties.In this paper,the Co-based amorphous alloys were prepared by rapid cooling on a single Cooper wheel in air atmosphere.The results of XRD and TEM analyses indicated that the alloy specimen was fully amorphous.The thermal stability and crystallization behavior of the alloy was studied by using the differential thermal analysis(DTA) in argon atmosphere,and glass transition temperature(Tg),crystallization temperatures(Txi),peak temperatures(Tpi) were determined at the heating rate of 5,10,15,35,55,75 and 95 K·min-1,respectively.It was found that Tg,Txi,Tpi of the amorphous alloy depended on the heating rate during the continuous heating,which suggested that both glass transition and crystallization had a significant kinetic effect.The kinetics of non-isothermal crystallization at constant heating rate,such as apparent crystallization activation energy,could be analyzed by the Kissinger and Doyle-Ozawa methods.A detailed interpretation of the results led to some interesting conclusions.The important results obtained were as follows: From the non-isothermal DTA thermo gram,it could show that the value of peak temperature of crystallization of the alloy increased with heating rate increasing.The apparent activation energy was variation with Tg,Tx and Tp suggested by Kissinger method.The average activation energy suggested by Doyle-Ozawa was similar as that obtained by Kissinger method.The curves of relation of crystallized fraction x with temperature or time at different heating rates exhibited as a function of "S" shape.更多还原