Hardness and shear band evolution in bulk metallic glasses after plastic deformation and annealing
Hardness and shear band evolution in bulk metallic glasses after plastic deformation and annealing
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DOI：
10.1016/j.actamat.2008.07.009
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发表时间：
2008-10
期刊：
影响因子：
9.4
通讯作者：
S. Xie;E. George
中科院分区：
文献类型：
--
作者：
S. Xie;E. George
应变引起的硬化和退火引起的软化在晶体金属中是典型的。大块金属玻璃(BMG)表现出相反的行为，即应变诱导软化和退火诱导硬化。此外，BMG在经历三步变形-退火-变形过程后出现可逆的软化-硬化-软化。变形和退火后的硬度变化与Vickers压痕周围/下面的剪切带图案有关。铸态BMG在压痕过程中产生的剪切带呈半圆形和放射状，与压痕下的应力分布一致。相反，预应变的BMG中的剪切带是不规则的和卷曲的，似乎是先前压缩过程中产生的剪切带和铸态BMG中的剪切带的混合物。经退火后，剪切带趋于恢复其半圆形和径向形状，与退火态的硬化一致。
Strain-induced hardening and annealing-induced softening are typical in crystalline metals. Bulk metallic glasses (BMG) exhibit the opposite behavior, namely, strain-induced softening and annealing-induced hardening. In addition, reversible softening–hardening–softening occurs in a BMG subjected to a three-step deformation–annealing–deformation process. The hardness changes after deformation and annealing can be correlated with the shear band patterns around/underneath Vickers indents. Shear bands produced during indentation of as-cast BMG are semicircular and radial, consistent with the stress distribution beneath the indenter. In contrast, the shear bands in the pre-strained BMG are irregular and convoluted, and appear to be a mixture of the shear bands produced during the prior compression and those in the as-cast BMG. After annealing, the shear bands tend to recover their semicircular and radial shapes consistent with the annealing-induced hardening.