Physikingenieurwesen (PHY)
Refine
Publication Type
- Article (26)
- Conference Proceeding (2)
- Part of a Book (1)
Keywords
- Additive manufacturing (1)
- High-entropy alloy (1)
- Laser metal deposition (1)
- Laser shock peeningFemtosecond laserNiTi alloyCorrosion behaviorLaser surface treatment (1)
- Powder blend (1)
- Refractory (1)
- laser mode locking; polymerisation; optical waveguides; high-speed optical techniques; two-photon processes; optical pulse compression; optical saturable absorption; integrated optics; semiconductor lasers (1)
- laser nitriding; wear resistance; NiTi alloy; roughness; microhardness (1)
- laser shock peeningfemtosecond laserNiTi alloymicrohardness (1)
In this work, the authors report on investigations of two-photon lithography of positive photoresist. The dependency of the pattern linewidth on variation in the processing parameters, like the laser patterning velocity or power of the femtosecond laser oscillator, is presented. The influence of the scan velocity between 0.38 and 1.90 mm/s on the resolution is discussed for a layer thickness of 3.5 μm. By using a commercial positive photoresist, an aspect ratio of 5 has been realized for grid structures and the qualities of the produced structures are discussed.
Progress in materials development is often paced by the time required to produce and evaluate a large number of alloys with different chemical compositions. This applies especially to refractory high-entropy alloys (RHEAs), which are difficult to synthesize and process by conventional methods. To evaluate a possible way to accelerate the process, high-throughput laser metal deposition was used in this work to prepare a quinary RHEA, TiZrNbHfTa, as well as its quaternary and ternary subsystems by in-situ alloying of elemental powders. Compositionally graded variants of the quinary RHEA were also analyzed. Our results show that the influence of various parameters such as powder shape and purity, alloy composition, and especially the solidification range, on the processability, microstructure, porosity, and mechanical properties can be investigated rapidly. The strength of these alloys was mainly affected by the oxygen and nitrogen contents of the starting powders, while substitutional solid solution strengthening played a minor role.
Studies on ultra-short pulsed laser shock peening of stainless-steel in different confinement media
(2020)
We investigate the role of liquid confinement media on ultra-short pulsed Laser Shock Peening (LSP). The LSP of stainless-steel 316 and 316 L was studied using Ti: Sapphire laser pulses of about 2 ps duration, maximum energy of about 1 mJ and pulse repetition rate of 5 kHz in different liquid confinement media of Ethanol, Deionized water and separate aqueous solutions of NaCl and Glycerol. It is found that the laser fluence and/or energy attenuating mechanisms like self-focusing, filamentation, plasma breakdown in the confinement media are less significant with ps laser pulses than those with sub-ps or fs pulse durations. It is shown that the resulting surface hardness of the peened steel as a function of laser fluence depends significantly on the confinement media and the relative increase in the hardness increases monotonically with the acoustic impedance of the liquid of the confinement medium used during …