Effect of electrospark doping on mechanical properties of Al-Si-Cu alloys

Introduction. Microhardness and wear resistance of the aluminum alloy (AK5M7) after its surface treatment through electrospark doping (ESD) using A (Cu) and P (Cu+P) electrodes with different applied energy is considered. The work objective is to study the relationship of the physicomechanical and strength properties of the surface of AK5M7 alloy obtained after ESD with copper and copper-phosphorus electrodes.Materials and Methods. X-ray diffraction and X-ray fluorescence analysis methods were used to determine the phase composition, coherent-scattering regions (CSR), and the surface microstrain.Research Results. It is established that with increasing energy, the values of microhardness and wear resistance increase when using both electrodes. The sample was modified by P electrode with the energy of 0.79 J. In this case, the maximum value of microhardness increased 5.3 times, wear resistance -1.6 times. It is found that with ESD, new intermetallic phases of Al2Cu and Cu3P are formed on the surface of the alloy under study. If the value of the energy used is maximum (0.79 J), the concentration of the Al2Cu phase increases 5 and 9 times with A and P electrodes, respectively, and the concentration of the Cu3P phase increases more than 4 times when using P electrode. The experimental data obtained suggest size reduction of the CSR and an increase in the microstrain values for all the Al, Al2Cu, and Cu3P phases on the surface.Discussion and Conclusions. An increase in energy with the ESD involves an increase in the defective factors and a change in the phase composition of the newly obtained surfaces. This may explain the increase in wear resistance of the surface

Optical Properties of LiGdF₄ Single Crystal in the Terahertz and Infrared Ranges

The basic mechanisms of absorption of THz range radiation in optically perfect LiGdF4 single crystals were studied using the broadband experimental data and the dielectric response function analysis within the harmonic oscillator model. The polarized IR reflection spectra have allowed one to determine the phonon contribution in the absorption coefficient in the THz range, while transmission spectra in the THz range were used to obtain the birefringence value and the effects of various mulitparticle processes. Additionally, we established the optical and electrodynamic parameters of the LiGdF4 single crystal, which are necessary for the design of nonlinear optical devices