نتایج جستجو برای: laser melting
تعداد نتایج: 207729 فیلتر نتایج به سال:
A new method for the estimation of properties of pure organic compounds is presented. Estimation is performed at three levels. The primary level uses contributions from simple groups that allow describing a wide variety of organic compounds while the higher levels involves polyfunctional and structural groups that provide more information about molecular fragments whose description through firs...
Differential scanning calorimetry (DSC) has been used to simulate laser fusion of ceramic precursors to prepare BSCCO high temperature superconducting materials. At fast heating rates, typical of the laser floating zone, the energy required for complete melting of the precursor increases with the Bi to Sr+Ca ratio, in agreement with the critical current results obtained. At low heating rates, s...
In rapid alloy solidification the dendrite-growth velocity depends sensitively on the deviations from local interfacial equilibrium manifested by kinetic effects such as solute trapping. The dendrite tip velocityundercooling function was measured in dilute Ni~Zr! over the range 1–25 m/s and 50–255 K using electromagnetic levitation techniques and compared to theoretical predictions of the model...
A new anode/cathode design and process concept for thin wafer based silicon devices is proposed to achieve the goal of providing improved control for activating the injecting layer and forming a good ohmic contact. The concept is based on laser annealing in a melting regime of a p-type anode layer covered with a thin titanium layer with high melting temperature and high laser light absorption. ...
The use of rapid prototyping (RP) technology for rapid tooling and rapid manufacturing has given rise to the development of application-oriented composites. The present paper furnishes succinct notes of the composites formed using main rapid prototyping processes such as Selective Laser Sintering/Melting, Laser Engineered Net Shaping, Laminated Object Manufacturing, Stereolithography, Fused Dep...
We investigate the dynamics of coherent optical phonons in tellurium after high-density excitation with femtosecond laser pulses. The data show a continuous redshift of the phonon frequency with increasing excitation density. Experiments with double-pulse excitation prove that the observed frequency shift is of purely electronic origin. We demonstrate that coherent phonons allow monitoring the ...
The nature of freezing and melting transitions for a system of hard disks in a spatially periodic external potential is studied using extensive Monte Carlo simulations. Detailed finite size scaling analysis of various thermodynamic quantities like the order parameter, its cumulants, etc., are used to map the phase diagram of the system for various values of the density and the amplitude of the ...
In this work, thermodynamic phenomena in crystalline silicon irradiated by an ultrafast laser pulse were studied using the method of molecular dynamics simulations. The Stillinger–Weber potential was used to model the crystalline silicon. The temperature development in silicon when heated by an ultrafast laser pulse was tracked. Melting and resolidification processes and the resulting structura...
Fundamentals of femtosecond laser pulse and nanoparticles are analyzed by a two-temperature model. Ultrafast surface melting, surface nanoengineering and shock wave impact are evident in the surface of graphite by femtosecond irradiation. The interaction between femtosecond laser pulses and Au/Ag nanoparticles has been investigated. Two effects are identified at different intensities: photofrag...
We use pulsed-laser heating of hydrogen at static pressures in the megabar pressure region to search for the plasma phase transition to liquid atomic metallic hydrogen. We heat our samples substantially above the melting line and observe a plateau in a temperature vs. laser power curve that otherwise increases with power. This anomaly in the heating curve appears correlated with theoretical pre...
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