Abstract The influence of shape and size of flaws on the strain energy, fracture toughness, and brittle to ductile transition mechanisms of Ni15Al70Co15 metallic glass material are carried out in this paper through a simulation of a tensile test. It is found that a less smooth flaw shape has a lower energy absorption capacity per unit volume because the wrinkle of the flaws spends the energy generated during the testing process. The flaw shapes strongly affect the fracture toughness while the flaw sizes decide the dominance in the competition between brittle and ductile fracture/deformation. The deformation forms from stress concentrations at flaw root/the sharp corner of the flaw and develops to the SBs, then shifts to shear transformation zones (STZs) within the small size. However, in the absence of the SBs within the large size of the flaw, the STZs are formed from the deformation embryos leading to display the essential characteristics of ductile fracture. Especially, for a circle flaw specimen with a large radius, the STZs plays a dominant role, leading to ductile fracture.

中文翻译：

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Ni15Al70Co15金属玻璃内裂纹形状和尺寸对断裂韧性及破坏机理的影响

摘要 本文通过拉伸试验模拟，研究了缺陷形状和尺寸对Ni15Al70Co15金属玻璃材料的应变能、断裂韧性和脆韧转变机制的影响。研究发现，缺陷形状越不光滑，单位体积的能量吸收能力就越低，因为缺陷的皱纹会消耗测试过程中产生的能量。缺陷形状强烈影响断裂韧性，而缺陷大小决定脆性和韧性断裂/变形之间竞争的主导地位。变形由裂纹根部/裂纹尖角处的应力集中形成，并发展到 SB，然后转移到小尺寸内的剪切转变区 (STZ)。然而，在大尺寸缺陷内没有 SB 的情况下，STZ 是由变形胚形成的，导致显示出韧性断裂的基本特征。特别是对于大半径的圆形缺陷试样，STZs起主导作用，导致塑性断裂。