基于Rietveld无标样定量研究HMX的β→δ等温相变动力学

Kinetics of β→δ isothermal phase transition of HMX based on quantitative phase analysis using the Rietveld method

以Rietveld无标样定量方法为基础,利用原位X射线粉末衍射技术(XRD)研究了奥克托今(HMX)的β→δ等温相变动力学。描述了不同温度下HMX的转变进度-时间曲线,求得Avrami指数n约为0.6,建立了相关的等温相变动力学方程。采用Arrhenius方程定量表示了速率常数k与温度T的关系,计算的活化能Ea约为151kJ/mol,指前因子lnA为36.2。结果表明:实验温度是影响相变的主导因素,HMX发生β→δ相变时,δ相近似于1维随机成核长大。

Based on the quantitative phase analysis using the Rietveld method, in-situ X-ray diffraction （XRD） experiments were conducted to explore β→δ isothermal phase transition kinetics of HMX. Transition extent-time curves of HMX were described at different isothermal temperatures, the Avrami exponent n was obtained close to 0.6, and the related isothermal phase transition kinetics equation was developed. The Arrhenius equation was used to quantify the relationship between the rate constant k and the temperature T, the calculated activation energy Ea was about 151 kJ/mol, and the calculated pre-exponential lnA was 36.2. The results show that the experimental temperature is the dominant factor controlling the β→δ phase transition of HMX, and δ phase experiences a similarly one-dimensional nucleation-and-growth mechanism randomly during the β→δ phase transition of HMX.