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Surface Modification of Metallic Targets with Ultrashort Laser Pulses

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Gakovic B., Stasic J., Petrovic S., Radak B., Krmpot A., Jelenkovic B., Trtica M.

Acta Physica Polonica A

2009

vol. 116

issue 4

611-613

Interaction of pulsed femtosecond Ti:sapphire laser (160 fs), operating at high repetition rate (75 MHz) at 800 nm, with nickel-based superalloy Inconel 600 and tungsten-titanium (WTi) target was studied. The WTi target was in form of thin film deposited on silicon substrate. Low laser fluence of maximum 50 mJ/cm^{2} had modified the target surface during irradiation/exposure time of seconds or minutes. The radiation absorbed from the laser beam generates at the surface a series of effects, such as direct material vaporization, formation of clusters, etc. Morphological features of the targets can be summarized as: (a) intensive removal of material and crater appearance; (b) creation of nanostructures; (c) microcracking, etc. Ablation of Inconel 600 surface is effective, resulting in formation of holes with small diameter ( ≤ 10 μm) and relatively large depth ( ≤ 50 μm). In case of WTi target/thin film, the surrounding rim is not so expressed, and crater depths are lower. It can be concluded that the average laser power of the order of watts, pulse energies of the order of nanojoules and high repetition rates (MHz range) can successfully modify metallic materials.

Laser Beam Profile Influence on Dark Hanle Resonances in Rb Vapor

100%

Krmpot A., Ćuk S., Nikolić S., Radonjić M., Grujić Z., Jelenković B.

Acta Physica Polonica A

2009

vol. 116

issue 4

563-565

Influence of two different laser beam profiles, the Gaussian and the Π (top hat) profile on the resonance line widths and amplitudes in the Hanle electromagnetically induced transparency was studied. The laser beam propagates through the vacuum Rb glass cell. Studies were done at D_1 line for the open ^{87}Rb: F_{g}=2 → F_{e}=1 transition. Hanle electromagnetically induced transparency was measured for the two beam profiles with the same total power and beam diameter and experimental results showed that Gaussian and the top hat profiles give different amplitudes and widths of the Hanle resonances. Resonances obtained from the top hat laser beam profile have lower amplitudes and higher line widths.

Fine-Scale Structure Investigation of Nimonic 263 Superalloy Surface Damaged by Femtosecond Laser Beam

100%

Milosavljevic A., Petronic S., Sreckovic M., Kovacevic A., Krmpot A., Kovacevic K.

Acta Physica Polonica A

2009

vol. 116

issue 4

553-556

Due to the specific conditions of manufacturing, processing and utilization of nickel-base superalloys, the implementation of contemporary precision techniques is necessary in the research of the alloys features. Multi-component nickel-base superalloys, with about of 50% of nickel content, are commonly exploited in the conditions of high temperatures and pressures as well as in various aggressive operating environments. For successful quality control, which includes the monitoring of the changes in the alloy microstructure, fine-scale structure investigations are necessary. In this work, the samples of nickel-base superalloys have been exposed to 800 nm femtosecond laser in various operating regimes. Surface damages and dents caused by femtosecond laser pulses have been observed by optical and scanning microscopy.

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3 Acta Physica Polonica A

3 2009

3 Krmpot A.

1 Gakovic B.

1 Grujić Z.

1 Jelenkovic B.

1 Jelenković B.

1 Kovacevic A.

1 Kovacevic K.

1 Milosavljevic A.

1 Nikolić S.

1 Petronic S.

1 Petrovic S.

1 Radak B.

1 Radonjić M.

1 Sreckovic M.

1 Stasic J.

1 Trtica M.

1 Ćuk S.

Search results

Surface Modification of Metallic Targets with Ultrashort Laser Pulses

Laser Beam Profile Influence on Dark Hanle Resonances in Rb Vapor

Fine-Scale Structure Investigation of Nimonic 263 Superalloy Surface Damaged by Femtosecond Laser Beam