Shen Lai-Quan, Yu Ji-Hao, Tang Xiao-Chang, Sun Bao-An, Liu Yan-Hui, Bai Hai-Yang, Wang Wei-Hua
Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China.
Sci Adv. 2021 Mar 31;7(14). doi: 10.1126/sciadv.abf7293. Print 2021 Mar.
Crack propagation is the major vehicle for material failure, but the mechanisms by which cracks propagate remain longstanding riddles, especially for glassy materials with a long-range disordered atomic structure. Recently, cavitation was proposed as an underlying mechanism governing the fracture of glasses, but experimental determination of the cavitation behavior of fracture is still lacking. Here, we present unambiguous experimental evidence to firmly establish the cavitation mechanism in the fracture of glasses. We show that crack propagation in various glasses is dominated by the self-organized nucleation, growth, and coalescence of nanocavities, eventually resulting in the nanopatterns on the fracture surfaces. The revealed cavitation-induced nanostructured fracture morphologies thus confirm the presence of nanoscale ductility in the fracture of nominally brittle glasses, which has been debated for decades. Our observations would aid a fundamental understanding of the failure of disordered systems and have implications for designing tougher glasses with excellent ductility.
裂纹扩展是材料失效的主要方式，但其扩展机制仍然是长期存在的谜题，尤其是对于具有长程无序原子结构的玻璃材料。最近，空化被提出作为控制玻璃断裂的潜在机制，但关于断裂时空化行为的实验测定仍然缺乏。在此，我们提供明确的实验证据，以确凿地确立玻璃断裂中的空化机制。我们表明，各种玻璃中的裂纹扩展由纳米空洞的自组织成核、生长和合并主导，最终在断面上形成纳米图案。由此揭示的空化诱导的纳米结构断裂形态证实了在名义上脆性的玻璃断裂中存在纳米尺度的延展性，这一问题已经争论了几十年。我们的观察将有助于从根本上理解无序系统的失效，并对设计具有优异延展性的更坚韧玻璃具有启示意义。
