Atomic-scale friction between single-asperity contacts unveiled through in situ transmission electron microscopy

X Wang and ZY Liu and Y He and SS Tan and GF Wang and SX Mao, NATURE NANOTECHNOLOGY, 17, 737-+ (2022).

DOI: 10.1038/s41565-022-01126-z

Friction and wear are detrimental to functionality and reduce the service life of products with mechanical elements. Here, we unveil the atomic-scale friction of a single tungsten asperity in real time through a high-resolution transmission electron microscopy investigation of a nanocontact in countermotion, induced through a piezo actuator. Molecular dynamics simulations provide insights into the sliding pathway of interface atoms and the dynamic strain/stress evolution at the interface. We observe a discrete stick-slip behaviour and an asynchronous process for the accumulation and dissipation of the strain energy together with the non-uniform motion of interface atoms. Our methodology allows for studying in situ atomic-friction phenomena and provides insights into friction phenomena at the atomic scale. Friction and wear at the atomic scale are hard to capture in experiment. Real- time in situ investigations of the countermotion of two touching tungsten asperities by means of high-resolution transmission electron microscopy unveil discrete stick-slip friction and molecular dynamics simulations provide insights into the sliding pathway of the atoms at the interface.

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