晶界内耗的影响因素和微观机制的进一步研究

项目名称： 晶界内耗的影响因素和微观机制的进一步研究

项目编号： No.10804108

项目类型： 青年科学基金项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 蒋卫斌

作者单位： 中国科学院合肥物质科学研究院

项目金额： 24万元

中文摘要： 本基金项目在前期工作的基础上，采用不同类型和不同取向差的双晶试样，研究单个晶界的内耗弛豫参量，试图进一步阐明晶界内耗峰的微观机制，从更深层次理解晶界内耗峰的机制及其与晶界结构的关系。研究了不同材料不同转轴不同取向差的单个晶界的内耗，观察到不同类型晶界内耗的弛豫参量有明显差别，并且发现不同类型的晶界弛豫过程中存在耦合效应或原子协同运动效应。 研究了双晶试样中晶界密度对晶界峰高度的影响。由于晶界结构没有发生变化，因此激活能和指数前因子等参数基本不变。但晶界内耗峰峰高与晶界密度大小成正比，这进一步证明了这个峰是由晶界运动引起的，而不是晶格位错的运动引起。这一结果进一步澄清了国际上对这个内耗峰起源的争论，从而在更深层次上阐明晶界内耗的微观机制。

中文关键词： 双晶;晶界;内耗;补偿效应;晶界密度

英文摘要： This project is a succession and further extension of our proceeding projects which were going to reveal the dependence of relaxation parameters upon boundary type. The temperature dependence of the grain boundary internal friction peak was determined, and the activation parameters of grain boundary relaxation were obtained. Experimental evidence is provided for the occurrence of the compensation effect for grain boundary internal friction. The compensation temperature divides the investigated temperature range of the internal friction peak into two regimes, with different relations between the magnitude of relaxation time and enthalpy of activation. In order to further confirm the origin of grain boundary (GB) internal friction peak in bicrystals, the effect of GB density on the internal friction peak in pure aluminum is studied. It is found that the increment of GB density leads to a proportional increment of the peak height, while the activation parameters remain unchanged. The results further confirm that the observed internal friction peak in bicrystals is induced by the GB. The origin of the internal friction peak is interpreted by stress induced GB sliding. Based on these works, the microscopic mechanism of grain boundary internal friction peak and its relation with boundary structure were further explained.

英文关键词： bicrystals; grain boundary; compensation effect;GB density