Shear transformation zone volume determining ductile–brittle transition of bulk metallic glasses
Shear transformation zone volume determining ductile–brittle transition of bulk metallic glasses
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DOI：
10.1016/j.actamat.2010.12.006
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发表时间：
2011-03
期刊：
影响因子：
9.4
通讯作者：
F. Jiang;M. Jiang;H. Wang;Yanglei Zhao;L. He;Jun Sun
中科院分区：
文献类型：
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作者：
F. Jiang;M. Jiang;H. Wang;Yanglei Zhao;L. He;Jun Sun
对Zr 52.5Cu 17.9Ni 14.6Al 10 Ti 5（Vit 105）块体非晶合金的铸态和退火态试样进行了从室温（293 K）到液氮温度（77 K）的三点弯曲实验。结果表明，自由体积的减少，由于退火和/或低温温度可以减少的倾向，形成多个剪切带，从而恶化塑性变形能力。我们清楚地观察到一个尖锐的韧脆转变（DBT），在微观断裂特征转移从微米尺度的静脉图案到纳米尺度的周期性波纹。宏观上，相应的断裂模式由韧性剪切断裂转变为脆性拉伸断裂。提出了考虑自由体积、温度和应变速率的剪切转变区体积来定量表征金属玻璃断裂中的DBT行为。
Three-point bending experiments were performed on as-cast and annealed samples of Zr52.5Cu17.9Ni14.6Al10Ti5(Vit105) bulk metallic glasses over a wide range of temperatures varying from room temperature (293K) to liquid nitrogen temperature (77K). The results demonstrated that the free volume decrease due to annealing and/or cryogenic temperature can reduce the propensity for the formation of multiple shear bands and hence deteriorate plastic deformation ability. We clearly observed a sharp ductile-to-brittle transition (DBT), across which microscopic fracture feature transfers from micro-scale vein patterns to nano-scale periodic corrugations. Macroscopically, the corresponding fracture mode changes from ductile shear fracture to brittle tensile fracture. The shear transformation zone volume, taking into account free volume, temperature and strain rate, is proposed to quantitatively characterize the DBT behavior in fracture of metallic glasses.