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首页> 外文期刊>International journal of nanomechanics science and technology >STRUCTURE FORMATION AND CHANGES IN THE REACTIVITY OF COMPOSITE GRANULES OF THE Nb-Si SYSTEM IN MECHANICAL ACTIVATION
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STRUCTURE FORMATION AND CHANGES IN THE REACTIVITY OF COMPOSITE GRANULES OF THE Nb-Si SYSTEM IN MECHANICAL ACTIVATION

机译：机械活化过程中Nb-Si体系复合颗粒活性的结构形成与变化

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摘要

The basic laws governing the structure formation and changes in the activity of composite granules of the Nb-Si system in mechanical activation in order to reach maximum efficiency of the subsequent synthesis of niobium silicides have been considered. The mechanical activation of composite granules was performed using a Retsch PM 400 planetary mill. The activity, characterizing integrally the energy intensity and the reactivity of composite granules, was evaluated by the velocity of propagation of the front of the linearly organized reaction of niobium silicides synthesis. The structure was investigated with the aid of a light and an electronic microscope, as well as an X-ray diffractometer. Typical structures of composite granules and the charts of changes in their activity as a function of processing time are presented. The initial growth of activity is conditioned by the increasing uniformity of distribution and enlargement of the contact area of niobium and silicon, decrease in the share of niobium defect regions, not containing silicon, and accumulation of internal energy related to the increasing imperfection of the crystalline structure of the components. A decrease in the activity after reaching the maximum is related to chemical interaction of the components in microvolumes of composite granules and relaxation of the accumulated energy. We identified the structuring role of silicon: its nanosized particles, having superhigh conglomeration capacity, capture and bond the niobium particles, thus ensuring the formation of structures of composite granules. The regions of niobium that are free from silicon represent the basic structural defect of granules. An increase in the mechanical activation time results in thinning of the niobium particles and silicon layers, thus generating a more homogeneous structure and reducing the relative volume of defect regions. The optimal time of silicon preprocessing was found to be 60 min. The Nb_5Si_3 composite granules have the maximum activity after 180 min of mechanical activation, while Nb_3Si granules after 260 min.
机译：已经考虑了基本法则，该法则控制着Nb-Si系统复合颗粒在机械活化中的结构形成和活性变化，以达到随后合成硅化铌的最大效率。复合颗粒的机械活化是使用Retsch PM 400行星式粉碎机进行的。通过铌化硅化物合成的线性组织反应前沿的传播速度，可以评估表征颗粒复合材料能量强度和反应活性的整体活性。借助于光和电子显微镜以及X射线衍射仪研究了该结构。给出了复合颗粒的典型结构及其活性随加工时间变化的图表。活性的初始增长受到以下因素的制约：铌和硅的分布均匀性增加和接触面积增大，不包含硅的铌缺陷区域份额的减少以及与晶体不完善性有关的内部能量的积累组件的结构。达到最大值后活性降低与复合颗粒微体积中各组分的化学相互作用和累积能量的松弛有关。我们确定了硅的结构作用：具有超高凝聚能力的纳米颗粒捕获并结合了铌颗粒，从而确保了复合颗粒结构的形成。不含硅的铌区域代表了颗粒的基本结构缺陷。机械活化时间的增加导致铌颗粒和硅层的变薄，从而产生更均匀的结构并减少了缺陷区域的相对体积。发现硅预处理的最佳时间为60分钟。机械活化180分钟后，Nb_5Si_3复合颗粒具有最大活性，而260分钟后，Nb_3Si颗粒具有最大活性。

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