ABSTRACT

Pulsed laser processing is a manufacturing method that uses ultrafast laser pulses to precisely fabricate three-dimensional objects. Among the tunable parameters in pulsed laser processing, the laser repetition rate (the number of laser pulses per second) has only recently been recognized as essential for controlling the affected depth of laser ablation, sintering, and melting processes. This depth limit determines the resolution and efficiency of pulsed laser technologies for micro-/nano-electronics and aerospace and nuclear applications. This project aims to explore the minimum achievable depth when the laser repetition rate increases to the giga-/terahertz regime. A set of advanced computational tools will be developed and implemented to understand the laser and materials interactions under extreme conditions. Successful completion of this project will enable confined heating of ultrahigh-repetition-rate lasers to the nanoscale, thereby improving the precision and efficiency of ablation, melting, and sintering of nano-layers at material surfaces. The research team will also develop education programs on thermal transport and laser manufacturing at the extremes to impact and inspire broad audiences, from local K-12 students to students at the University of Nevada, Reno. Open-source code developed from the project will be deployed at nanoHUB.org and accessible to both academia and industry.

The overarching goals of this project are to predict and control the depth of the heat-affected zone during ultrahigh-repetition-rate laser processing, to model the unique microstructure behaviors of laser-material interactions under extreme conditions, and to develop and apply advanced thermomechanical models to predict the material responses to laser processing. Specifically, the research team will develop, validate, and share advanced computational models for predicting thermal transport behaviors for a broad range of materials under pulsed laser heating at repetition rates up to the terahertz regime. Moreover, the PIs will develop thermomechanical models?synergizing the power of the phase field method, molecular dynamics, and Boltzmann transport equations?for predicting the poorly understood material behaviors and properties during and after ultrahigh-repetition-rate laser processing. The process-structure-property relations for ultrahigh-repetition-rate laser processing will be established through this project. Such knowledge will enable the development of ultra-precise, fast, and efficient laser manufacturing technologies via nano-confined heating.

This project is jointly funded by the Thermal Transport Processes program and the Established Program to Stimulate Competitive Research (EPSCoR).

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

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