Fatigue and fracture behavior of bulk metallic glass
Fatigue and fracture behavior of bulk metallic glass
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DOI：
10.1007/s11661-004-0186-5
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发表时间：
2004-11
期刊：
影响因子：
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通讯作者：
Zhefeng Zhang;J. Eckert;L. Schultz
中科院分区：
文献类型：
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作者：
Zhefeng Zhang;J. Eckert;L. Schultz
对Zr52.5Cu17.9Al10Ni14.6Ti5大块金属玻璃进行了室温拉伸、压缩、循环拉伸-拉伸和循环压缩-压缩试验，以全面了解其损伤和断裂机制。在拉伸载荷下，金属玻璃仅表现出弹性变形，然后发生脆性剪切断裂。在压缩载荷下，弹性变形后，在最终剪切断裂之前可以观察到明显的塑性（0.5至0.8%）。压缩下的断裂强度略高于拉伸下的断裂强度。压缩和拉伸作用下的剪切断裂不会沿最大剪应力平面发生。这表明金属玻璃的断裂行为不遵循Tresca准则。断裂面表现出明显不同的特征，即均匀的脉结构（压缩断裂）和与辐射脉共存的圆形核心（拉伸断裂）。在循环拉-拉载荷作用下，疲劳裂纹首先沿试件表面的局部剪切带萌生，然后沿基本垂直于应力轴的平面扩展。在循环压缩-压缩载荷作用下存在表面损伤层。然而，最终的破坏也表现出单轴压缩下的纯剪切断裂特征。在相同应力比下，金属玻璃的循环压缩-压缩疲劳寿命比循环拉-拉疲劳寿命高约10倍。基于这些结果，阐明了单轴和循环载荷引起的金属玻璃的损伤和断裂机制。
Tensile, compressive, cyclic tension-tension, and cyclic compression-compression tests at room temperature were systematically applied to a Zr52.5Cu17.9Al10Ni14.6Ti5bulk metallic glass for comprehensive understanding of its damage and fracture mechanisms. Under tensile loading, the metallic glass only displays elastic deformation followed by brittle shear fracture. Under compressive loading, after elastic deformation, obvious plasticity (0.5 to 0.8 pct) can be observed before the final shear fracture. The fracture strength under compression is slightly higher than that under tension. The shear fracture under compression and tension does not occur along the maximum shear stress plane. This indicates that the fracture behavior of the metallic glass does not follow the Tresca criterion. The fracture surfaces show remarkably different features,i.e., a uniform vein structure (compressive fracture) and round cores coexisting with the radiating veins (tensile fracture). Under cyclic tension-tension loading, fatigue cracks are first initiated along localized shear bands on the specimen surface, then propagated along a plane basically perpendicular to the stress axis. A surface damage layer exists under cyclic compression-compression loading. However, the final failure also exhibits a pure shear fracture feature as under uniaxial compression. The cyclic compression-compression fatigue life of the metallic glass is about a factor of 10 higher than the cyclic tension-tension fatigue life at the same stress ratio. Based on these results, the damage and fracture mechanisms of the metallic glass induced by uniaxial and cyclic loading are elucidated.