AgNi15 composite particles prepared by ultrasonic arc spray atomization method

Ultrasonic arc spray atomization (UASA) method was used to prepare high-melting-point, immiscible AgNi15 (mass fraction, %) composite particles. Sieving was used to determine the size distribution of the AgNi15 particles. The morphology, rapidly solidified structure and metastable solution expansion of the AgNi15 particles were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS), respectively. The results show that the AgNi15 composite particles are spherical and well-dispersed, and the mass fractions of the particles with diameters <74μm and <55 μm are 99.5% and 98%, respectively. The rapidly solidified structure of the AgNi15 particles consists of spherical nickel-richβ(Ni)-phase particles dispersed throughout a silver-richα(Ag)-phase matrix andα(Ag)-phase nanoparticles dispersed throughout largerβ(Ni)-phase particles. The silver and nickel in the AgNi15 particles form a reciprocally extended metastable solution, and the solid solubility of nickel in the silver matrix at room temperature is in the range of 0.16%?0.36% (mole fraction).

Numerical Simulation of Radial Ultrasonic Assisted MIG Welding Arc

The numerical simulation of arc was carried out for both conventional melt inert gas(MIG)welding and ultrasonic assisted melt inert gas(U-MIG)welding.Based on the model established by Fluent,the arc shape,temperature field,and potential distribution were simulated.The study found that the shape of the arc changed when ultrasonic was added radially;the high-temperature area of the arc stretched,and the temperature peak increased.But as the current increased,the increase in temperature decreased.In addition,under the same conditions,the potential of U-MIG decreased and the pressure on the workpiece increased.To verify the accuracy of the simulation results,welding experiments under identical conditions were carried out,and a high-speed camera was used to collect dynamic pictures of the arc.The simulation results were in a favorable agreement with the experimental results,which provided a certain reference value for ultrasonic assisted arc welding.

Improving Weld Quality by Arc-Excited Ultrasonic Treatment

Ultrasonic treatment of the solidifying metal is a promising method for improving the quality of fusion welding. A method to combine the ultrasonic waves to the welding process using arc excited ultrasonic emission, called arc ultrasonic, was high frequency modulation of the arc plasma. The effects of arc ultrasonic on the weld including the fusion zone, the partially melted zone and the heat affected zone are described. The arc ultrasonic energy changes the weld microstructure. In the fusion zone, the primary dendrite arm spacing decreases significantly and more acicular ferrite appears. In the partially melted zone, a large amount of fine grains appear. In the heat affected zone, the width of the tempered zone increases with increasing modulation frequency and the microstructure is refined. The results show that arc ultrasonic is a new and effective way for improving weld quality.