Al-Cu多晶锯齿形屈服现象中的尺度效应

对Al-Cu多晶合金锯齿形屈服现象中各特征物理量(应力跌幅、跌落时间和再加载时间)随应变演化的规律进行了系统研究，讨论了不同厚度试件演化结果的区别.同时，这种尺度效应还表现为相同加载条件下1，2mm厚度试件与3mm厚度试件的Portevin-Le Chrtelier (PLC)类型的差异.利用非线性时间序列分析的方法对前者在相空间中吸引子的几何特性进行了描述，并通过主分量分析的方法初步判定其中存在着混沌行为.后者演化过程中应力跌落事件按跌落幅度统计分布符合幂律规律，具有自组织临界性特征.最后，借助自组织 关键词： 锯齿形屈服 尺度效应 Al-Cu合金

Size effect on serrated yielding in Al-Cu polycrystals

In this paper, through a systematic statistical analysis of the characteristics of the serrated yielding, including the stress drop amplitude and the drop duration, etc., the difference between the results of thinner samples (1mm and 2mm) and those of thicker samples (3mm), has been reported. The size effect in Portevin-Le Chrtelier (PLC) effect also manifests itself in the difference of PLC types of jerky flow of 1mm or 2mm thick samples and those of 3mm thick samples under the same experimental conditions. Moreover, the geometrical characteristics of attractor of the former series in phase space are described by using methods of nonlinear time series analysis, and chaotic behavior is proved to exist in these series through the application of principal component analysis. The distribution of stress drops of the latter is found to follow a power-law distribution, which is referred to as the signature of self-organized criticality phenomenon.