Difference in compressive and tensile fracture mechanisms of Zr59CU20Al10Ni8Ti3 bulk metallic glass
Difference in compressive and tensile fracture mechanisms of Zr59CU20Al10Ni8Ti3 bulk metallic glass
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DOI：
10.1016/s1359-6454(02)00521-9
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发表时间：
2003-02
期刊：
影响因子：
9.4
通讯作者：
Zhefeng Zhang;J. Eckert;L. Schultz
中科院分区：
文献类型：
--
作者：
Zhefeng Zhang;J. Eckert;L. Schultz
研究了Zr59Cu20Al10Ni8Ti3大块非晶合金的压缩和拉伸变形以及断裂行为。结果表明，在压缩载荷作用下，金属玻璃在断裂前表现出一定的塑性。断裂主要集中在一个主剪切带上，应力轴与断裂面之间的压缩断裂角θC为43°。在拉伸载荷作用下，材料总是表现为脆性断裂而不屈服。拉伸断裂应力σFT约为1.58 GPa，低于压缩断裂应力σFC（=1.69 GPa）。应力轴与断裂面之间的拉伸断裂角θT等于54°。因此，θ C和θ T均偏离最大剪应力平面（45°），表明金属玻璃在压缩和拉伸载荷下的断裂行为不符合von Mises准则。扫描电子显微镜观察表明，金属玻璃的压缩断口主要由脉状结构组成。在拉伸断口上观察到脉状和放射状核的组合特征。在此基础上，考虑了正应力对非晶合金断裂过程的影响，讨论了非晶合金的断裂机制。结果表明，拉伸断裂首先在正应力作用下由辐射状核体产生，然后在剪应力作用下扩展，形成复合断裂特征。而金属玻璃的压缩断裂主要受剪应力的控制。θ C和θ T偏离45°的原因是断裂面上的正应力和剪应力的共同作用。
The compressive and tensile deformation, as well as the fracture behavior of a Zr59Cu20Al10Ni8Ti3bulk metallic glass were investigated. It was found that under compressive loading, the metallic glass displays some plasticity before fracture. The fracture is mainly localized on one major shear band and the compressive fracture angle, θC, between the stress axis and the fracture plane is 43°. Under tensile loading, the material always displays brittle fracture without yielding. The tensile fracture stress, σFT, is about 1.58 GPa, which is lower than the compressive fracture stress, σFC(=1.69 GPa). The tensile fracture angle, θT, between the stress axis and the fracture plane is equal to 54°. Therefore, both θCand θTdeviate from the maximum shear stress plane (45°), indicating that the fracture behavior of the metallic glass under compressive and tensile load does not follow the von Mises criterion. Scanning electron microscope observations reveal that the compressive fracture surfaces of the metallic glass mainly consist of a vein-like structure. A combined feature of veins and some radiate cores was observed on the tensile fracture surfaces. Based on these results, the fracture mechanisms of metallic glass are discussed by taking the effect of normal stress on the fracture process into account. It is proposed that tensile fracture first originates from the radiate cores induced by the normal stress, then propagates mainly driven by shear stress, leading to the formation of the combined fracture feature. In contrast, the compressive fracture of metallic glass is mainly controlled by the shear stress. It is suggested that the deviation of θCand θTfrom 45° can be attributed to a combined effect of the normal and shear stresses on the fracture plane.