锆基块体非晶合金剪切带扩展过程的“应变硬化现象”

“Strain Hardening Phenomenon”of Shear Bands Propagation Process of Zr-based Bulk Amorphous Alloys

选择典型的锆基块体非晶合金Vit.105（Zr52.5Cu17.9Ni14.6Al10Ti.5）,采用小高径比准静态压缩试验,对合金进行两种不同方式的加载。通过对不同变形模式试样自由体积及维氏硬度的测定,研究了非晶合金的应变诱发体积扩张特性;讨论了剪切带空间增殖的微观机制。结果表明,非晶合金中应变诱发体积扩张过程发生于剪切带外部仅经受弹性应变的区域;剪切带扩展是一个“软化-硬化”的动态过程,这为剪切带的空间增殖创造条件。

Choosing typical Zr-based BMGs Vit.105 （Zr52.5CUlT.9Ni14.6Al10Ti5） as object, adopting the quasi-static compression tests with small aspect ratio, the samples were conducted by two different loading modes. The stress-induced volume dilatation characteristic of amorphous alloys was investigated by the measurement of free volume and Vickers hardness of the samples with different deformation modes. The micro-mechanisms of shear band multiplication were discussed. The results show that the stress induced volume dilatation process in the amorphous alloys appear in the outside shear band regions which just undergoes elastic strain. The propagation of shear bands is ＂softening-hardening＂ dynamic process, which can create condition for the spatial multiplication of shear bands.