在结构非均匀的多晶材料中, 局域化塑性变形不仅在微观层次而且也在介观层次上具有波动特征, 并以塑性波形态进行扩展,这一现象与材料亚韧性断裂之间有相互关系.纳米晶、亚微米微晶2009铝合金试样在经受拉伸应力实验时,试样上各点的应变量在三维方向上均呈波动性变化,且随着外加载荷的增加而波动的幅度增加.塑性变形的波动的传播是在加载过程中, 试样内的剪切稳定性丧失后, 由于晶粒群转动,在试样上沿最大剪应力方向形成了吕得尔斯条带而逐步形成的.主剪切带形成了一个塑性变形的波峰, 接下去侧生条带和次生带形成波峰和波低谷区, 周而复始, 形成了塑性变形的波动的传播.应力应变峰值的形成与材料缺陷所造成应力集中有关.试样于应力集中点起始迅速开裂.宏观断裂强度仅体现了材质缺陷弥散程度的统计平均数.
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