Zr_(65)Al_(7.5)Ni_(10)Cu_(12.5)Ag_5非晶合金压痕下方剪切带形貌的研究

以Zr65Al7.5Ni10Cu12.5Ag5块体非晶合金作为研究对象,采用界面压痕技术和扫描电子显微镜,分别对铸态、轧制态以及轧制-退火态试样压痕下方的剪切带形貌进行了研究。实验结果表明,铸态试样以半圆形剪切带为主,同时存在少量的射线状剪切带,并且形貌比较规则;轧制态试样的剪切带形貌变得很不规则,很难分辨半圆形和射线状剪切带,并且随着变形量的增加,剪切带形貌的不规则程度增加;轧制-退火态试样中重新出现了规则的半圆形和射线状剪切带,变形量对剪切带形貌几乎没有影响。这些结果说明,轧制态试样压痕下方剪切带形貌不规则的主要原因是轧制变形使剪切带中自由体积含量显著增加。

Shear Band Patterns of Zr65Al7.5Ni10Cu12.5Ag5 Metallic Glass underneath Indentation

The shear band patterns underneath Vickers indents of Zr65Al7.5Ni10Cu12.5Ag5 bulk metallic glass in different conditions (the as-cast, the as-rolled, and the as-rolled and annealed) were investigated by use of the bonded interface technique and scanning electron microscopy. The results show that the plastic zone underneath indentation of the as-cast specimen is consisted of semicircular shear bands and infrequent radial shear bands, and the patterns are regular. The shear band patterns of the as-rolled specimens become irregular, and it is difficult to recognize the semicircular and radial shear bands from the plastic zone underneath indentation, and the irregular degree of shear band patterns increases with the increase of thickness reduction. The plastic zone of the as-rolled and annealed specimens recovers regular semicircular and radial shear bands as observed in the as-cast specimen, and the minor effect of thickness reduction on the shear band patterns is found. All the results indicate that the reason of irregular shear band patterns underneath indentation of the as-rolled specimen is the prominent increase of free volume content in shear bands introduced by rolling deformation