Examination of nanosecond laser melting thresholds in refractory metals by shear wave acoustics
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Date
2017-07-12
Authors
Abdullaev, A.
Muminov, B.
Rakhymzhanov, A.
Mynbayev, N.
Utegulov, Z. N.
Journal Title
Journal ISSN
Volume Title
Publisher
American Institute of Physics
Abstract
Nanosecond laser pulse-induced melting thresholds in refractory (Nb, Mo, Ta and W)
metals are measured using detected laser-generated acoustic shear waves. Obtained
melting threshold values were found to be scaled with corresponding melting point temperatures of investigated materials displaying dissimilar shearing behavior. The experiments were conducted with motorized control of the incident laser pulse energies with small and uniform energy increments to reach high measurement accuracy and real-time monitoring of the epicentral acoustic waveforms from the opposite side of irradiated sample plates. Measured results were found to be in good agreement with numerical finite element model solving coupled elastodynamic and thermal conduction governing equations on structured quadrilateral mesh. Solid-melt phase transition was handled by means of apparent heat capacity method. The onset of melting was attributed to vanished shear modulus and rapid radial molten pool propagation within laser-heated metal leading to preferential generation of transverse acoustic waves from sources surrounding the molten mass resulting in the delay of shear wave transit times. Developed laser-based technique aims for applications involving remote examination of rapid melting processes of materials present in harsh environment (e.g. spent nuclear fuels) with high spatio-temporal resolution. © 2017 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). [http://dx.doi.org/10.1063/1.4993591]
Description
Keywords
nanosecond laser, waves, Solid-melt phase, laser-based technique
Citation
Abdullaev, A. et al.(>4), 2017(July 12), Examination of nanosecond laser melting thresholds in refractory metals by shear wave acoustics, American Institute of Physics