基于热分析的非晶合金非等温晶化动力学参数计算

Calculation about kinetic parameters for non-isothermal crystallization of amorphous alloy based on thermal analysis techniques

为了对非晶合金晶化动力学参数的各种计算方法的优缺点进行分析比较,为正确合理的选用数据处理方法提供依据,介绍了非等温晶化激活能及晶化机理函数的各种计算方法及其计算原理,并进行了数学归纳.分析表明,在计算激活能的各种方法中,无模式等转化率法是最可靠的一类方法,分为晶化速率-等晶化体积分数法、基于温度积分近似解析解的等晶化体积分数法、最大速率法3种类型.当热分析曲线基线难以精确确定时,用第二种类型计算出的激活能比第一种类型精度高.在确定机理函数的两种方法(Surinach曲线拟合法和Popesc曲线拟合法)中,Popesc法可以直接利用实验数据的积分而不需要提前知道速度常数和激活能,其结果的可靠性更高.

To correctly select calculation methods of the kinetic parameters for non-isothermal crystallization of amorphous alloys,the methods and their principia to calculate activation energy and determine the kinetic model of non-isothermal crystallization were introduced and summarized in mathematics.Analyses indicate that model-free isoconversion methods are the most reliable ones.And they are categorized into three groups,namely the rate-isoconversion methods,the isoconversion methods based on temperature integral approximations,and maximum rate methods.In the case of uncertainty over baselines of the thermal analysis data existing,the second group methods give more accurate activation energy values than the first group methods.For the two methods to determine the kinetic model,namely Suriach curve fitting procedure and Popesc curve fitting procedure,the Popesc curve fitting procedure is less affected by errors and gives more reliable results.Because it can conduct data obtained from experiments carried out under various heating rates without preliminary computation or assumption of the conversion rate constant.