Unraveling the fracture and failure mechanisms of molybdenum disulfide with various crystalline structures

Abhiram, B.R., Ponomarev, Ilia and Polcar, Tomas (2025) Unraveling the fracture and failure mechanisms of molybdenum disulfide with various crystalline structures. Engineering Fracture Mechanics, 316, [110858]. (doi:10.1016/J.ENGFRACMECH.2025.110858).

Abstract

Molybdenum disulfide (MoS₂) is recognized for its mechanical robustness and exceptional lubricity under extreme conditions. However, its fracture behavior remains relatively unexplored, particularly across different crystalline configurations. We perform reactive molecular dynamics simulations to investigate the role of crystallinity on the fracture properties and behavior of MoS₂ . In a departure from prior studies focused on specific crystal orientations, we examine a spectrum of crystallinity, ranging from perfect crystal to polycrystalline to amorphous structures. Fracture properties are measured using the J-integral, ultimate strain, and brittleness index. Our results indicate that the presence of grain boundaries and amorphous regions within polycrystalline MoS₂
enhances ductility and fracture toughness. However, at high degrees of crystallinity, grain boundaries dominate and act as a potential regions of defect, promoting crack propagation. Through an analysis of grain boundary interactions and atomic strain profiles, we elucidate critical insights into the mechanisms driving the observed variations in fracture properties. This study highlights the potential for tuning MoS₂ crystallinity to optimize its fracture toughness, advancing its application in challenging engineering environments.

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Contributors

Author: Tomas Polcar

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