High fracture toughness in van der Waals-layered MoTe2: Disappearance of stress singularity

In this study, we demonstrated that van der Waals-layered MoTe2 , where two-dimensional atomic layers are closely laminated by weak interactions, has higher fracture toughness in out-of-plane cracks than that in in-plane cracks owing to structural anisotropy. In situ electron microscopy fracture toughness tests were performed on micro-sized specimens. The apparent fracture toughness of the out-of-plane crack based on the continuum assumption was approximately twice that of the in-plane crack. In the out-of-plane crack specimen, as the loading progressed, inter -laminar slip occurred between layers, and this discrete nature caused the stress singularity to disappear, leading to high fracture toughness.

Automated summary

In this study, it was demonstrated that van der Waals-layered MoTe2, with its closely laminated two-dimensional atomic layers through weak interactions, exhibits higher fracture toughness in out-of-plane cracks compared to in-plane cracks due to structural anisotropy. In situ electron microscopy fracture toughness tests showed that the apparent fracture toughness of the out-of-plane crack was approximately twice that of the in-plane crack based on the continuum assumption. As loading progressed in the out-of-plane crack specimen, inter-laminar slip occurred between the layers, and this discrete nature resulted in the disappearance of stress singularity, leading to high fracture toughness.