Synthesis and characterization of Cu-ZrB2 alloy produced by PM techniques

The copper alloy with 7vol.% ZrB2 examined in this study was consolidated via powder metallurgy processing (PM) by combining mechanical alloying and hot pressing process. Structural changes, morphological properties and elemental analysis of the hotpressed samples were studied as a function of milling time with the use of X-ray diffraction, scanning electron microscopy (SEM) equipped with an energy dispersive X-ray spectrometry (EDS). Also, mechanical properties of the Cu-7vol.%ZrB2 alloy was investigated. Distribution of ZrB2 particles and presence of agglomerates in the Cu matrix directly depend on the milling time and show strong influence on hardness, compressive and electrical properties of Cu-ZrB2 alloys. [Projekat Ministarstva nauke Republike Srbije, br. 172005

Surface Modification of Metallic Targets with Ultrashort Laser Pulses

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 ( LT = 10 mu m) and relatively large depth ( LT = 50 mu m). 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.International School and Conference on Photonics (PHOTONICA09), Aug 24-28, 2009, Belgrade, Serbi

Tungsten modification induced by femtosecond laser with 1014 W/cm2 intensity in vacuum

Irradiation of refractory metals including tungsten (W) by high intensity laser radiation possesses fundamental as well as applied significance. Due to extraordinary characteristics, tungsten is nowadays an interesting metal which can be used in wide range of applications, from electronic to nuclear field. In the latter area, it is well known that tungsten can be used as plasma-facing material in fusion device/reactor [1] where high fluxes are present. Behavior/modification of tungsten surface under the action of high intensity laser radiation is scarce in literature and the goal of this research is focused in that direction. Tungsten modification in this study was done by pulsed, femtosecond laser [2,3] with the following parameters: output pulse energy up to 12 mJ; emission wavelength 800 nm; laser pulse duration 60 fs; repetition rate up to 10 Hz; fluence and intensity 16.2 J/cm2 and 2.7 1014 W/cm2 ,respectively (focusing regime), etc. Irradiation was carried out in vacuum, helium and air ambience. Generally, surface modification of the tungsten depends on the laser output parameters - pulse energy density (fluence), intensity, wavelength, laser pulse duration, number of accumulated laser pulses, etc., as well as the sample characteristics, for example absorptivity, and used environmental conditions (e.g. vacuum or gas (helium, air, etc.)). Surface changes and phenomena at W-target, in vacuum ambience, can be summarized as follows: (i) crater shaped damages with depth increasing with higher number of accumulated laser pulses; (ii) formation of solid droplets at near and further periphery; (iii) vast rim surrounding craters, and (iv) appearance of intensive plasma.VI International School and Conference on Photonics and COST actions: MP1406 and MP1402 : PHOTONICA2017 : August 23 - September 1, 2017; Belgrade

In-situ processing of TiB2 nanoparticle-reinforced copper matrix composites

In order to produce the composite powder analyzed in this paper, two prealloys were melted and afterwards gas atomized. The obtained TiB2-reinforced copper powder was consolidated by hot isostatic pressing (HIP). Since it is known that a decrease in the size of the reinforcing phase can cause an increase in hardness of composites, the main aim of the experimental work was to obtain as small particles of the dispersed phase as possible by using standard powder metallurgy techniques. Microstructure and microhardness of the ascast prealloys, as-atomized powder and HIP-ed compacts were examined. The results of these examinations revealed that TiB2 particles about 10 nm in size were in-situ formed and homogenously dispersed in the copper matrix. As a consequence of the TiB2 formation, the microhardness of Cu-TiB2 composite was significantly improved

The influence of applying the additional continuous laser on the synthesis of silicon-based nanoparticles by picosecond laser ablation in liquid

Silicon-based nanoparticles are synthesized by picosecond laser ablation in liquid using silicon single-crystal plates as targets. We demonstrated that applying the additional continuous laser immediately prior to and during the ablation changed the size distribution and oxygen content of the nanoparticles produced. This opens up the possibility of using the continuous laser as a simple tool for tailoring nanoparticle properties

Laser ablation and structuring of hard coating with ultra-short laser pulses

For material processing one of the main advantages of using ultra short laser pulses, comparing to long pulses, is the highly localized modification. Ultra short pulse laser modification of materials is valuable for their application in nanotechnology, tribology, microelectronics, medical application, etc. In this paper, special attention is paid to experimental investigations of femtosecond laser surface modification of hard protective coating. The sample has been processed by a Ti:sapphire laser with pulse duration of 200 fs and wavelength of 775 nm. Single and multi pulse irradiation were performed in air. Various analytical techniques were used for characterization. The damage threshold for the examined coating, irradiated by 200 fs pulses, was determine

Femtosecond laser ablation of alumina (Al2O3) from a multilayered coating

III International School and Conference on Photonics : PHOTONICA2011 : book of abstracts; August 29- September 2, 2011; Belgrad

Laser ablation and structuring of hard coating with ultra-short laser pulses

For material processing one of the main advantages of using ultra short laser pulses, comparing to long pulses, is the highly localized modification. Ultra short pulse laser modification of materials is valuable for their application in nanotechnology, tribology, microelectronics, medical application, etc. In this paper, special attention is paid to experimental investigations of femtosecond laser surface modification of hard protective coating. The sample has been processed by a Ti:sapphire laser with pulse duration of 200 fs and wavelength of 775 nm. Single and multi pulse irradiation were performed in air. Various analytical techniques were used for characterization. The damage threshold for the examined coating, irradiated by 200 fs pulses, was determine