Picosecond laser ablation of nickel-based superalloy C263 |
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Authors: | N G Semaltianos W Perrie J Cheng P French M Sharp G Dearden and K G Watkins |
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Institution: | (1) Department of Materials Science and Engineering, The University of Michigan, Ann Arbor, MI 48109, USA;(2) Applied Physics Program, University of Michigan, Ann Arbor, MI 48109, USA |
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Abstract: | Picosecond laser (10.4 ps, 1064 nm) ablation of the nickel-based superalloy C263 is investigated at different pulse repetition
rates (5, 10, 20, and 50 kHz). The two ablation regimes corresponding to ablation dominated by the optical penetration depth
at low fluences and of the electron thermal diffusion length at high fluences are clearly identified from the change of the
surface morphology of single pulse ablated craters (dimples) with fluence. The two corresponding thresholds were measured
as F
th(D1)1=0.68±0.02 J/cm2 and F
th(D2)1=2.64±0.27 J/cm2 from data of the crater diameters D
1,2 versus peak fluence. The surface morphology of macroscopic areas processed with a scanning laser beam at different fluences
is characterised by ripples at low fluences. As the fluence increases, randomly distributed areas among the ripples are formed
which appear featureless due to melting and joining of the ripples while at high fluences the whole irradiated surface becomes
grainy due to melting, splashing of the melt and subsequent resolidification. The throughput of ablation becomes maximal when
machining at high pulse repetition rates and with a relatively low fluence, while at the same time the surface roughness is
kept low. |
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Keywords: | |
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