Al-4%Cu多晶合金中锯齿形屈服现象的初步时序分析

对Al-4％Cu合金试样拉伸实验的锯齿形应力曲线进行了系统的统计分析，研究了锯齿应力跌幅、跌落时间以及再加载时间等特征物理量随应变、试样厚度和加载应变率的时序演化规律．结果表明，跌落时间对应变不敏感；1和2mm厚试样的平均应力跌幅和平均再加载时间均随应变线性增加，3mm厚试样的统计结果比较复杂．展示了PLC效应中自组织临界性存在的证据，并通过与经典沙堆模型的对比，结合动态应变时效原理和位错理论，解释了PLC变形带形成的非线性机制．

Preliminary Time Series Analysis of Serrated Yielding in Al-4%Cu Alloy

A systematic statistical analysis of the characteristics of the Portevin-Le Chartelier (PLC) effect in Al-4%Cu alloy, including the stress drop amplitude and the reloading time, etc., is carried out. The drop duration is found to be a constant independent of the strain. The average stress drop amplitude and the average reloading time of 1 and 2 mm thick samples increase with strain linearly, while the cases of 3 mm thick samples are much more complicated. The evidence of self-organized criticality is demonstrated, and the nonlinear mechanism in the PLC effect is also explained by comparing with the classic sand-pile model, and by combining with the dynamic strain aging (DSA) principle and the dislocation dynamics.