Atomic-scale mechanisms of femtosecond laser double-pulse sintering in Cu nanoparticles: A multiscale simulation study

YZ Huang and WY Tang and Z Yu and XC Xu and F He, ADVANCED POWDER TECHNOLOGY, 36, 105113 (2025).

DOI: 10.1016/j.apt.2025.105113

Femtosecond laser sintering offers a promising route for fabricating Cu- based micro- and nano-devices, yet optimizing processing conditions to balance sintering efficiency with minimal thermal damage remains challenging. In this study, a comprehensive multi-scale investigation of dual-pulse femtosecond laser sintering of Cu nanoparticles is presented using a combined molecular dynamics and twotemperature model (MD-TTM) simulation framework. Initially, the nanoscale melting point was determined under both slow and rapid heating conditions, revealing a reduction compared to bulk copper due to size effects. Subsequent simulations explored the effects of inter-pulse delay and energy distribution on electron-lattice energy coupling and sintering kinetics. Our results indicate that, within a critical delay threshold (approximately 30 ps), dual-pulse processing can synergistically regulate electron temperature, suppress thermionic emission, and accelerate neck formation. Furthermore, by comparing different energy injection schemes, we found that while a high-low energy combination improves processing speed, an equal energy ratio yields the best overall balance between electron temperature control and morphological evolution. These findings provide theoretical guidance for tailoring dualpulse laser parameters, offering enhanced process controllability and improved material quality for advanced laser sintering applications. (c) 2025 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

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