Study of the phase composition and electrical conductivity of the Cu-Cr-Si-Ce-La system alloys

The phase composition and electrical conductivity of 12 as-cast samples of the Cu-Cr-Si-Ce-La system alloys were investigated. The concentration of chromium in the samples ranged from 0.5 to 1.0 wt. %; the concentration of silicon in samples was from 0.1 to 1.3 wt. %; the concentrations of rare-earth metals (cerium and lanthanum) ranged from 0.1 to 0.5 wt. %. The samples were studied by scanning electron microscopy and micro-X-ray spectral analysis, as well as by X-ray phase analysis. It is established that in the experimental samples in equilibrium with a solid solution based on copper, depending on the concentration of the alloying elements, intermetallides Cu6Ce and Cu6La, inclusions of metallic chromium, chromium silicides Cr3Si and Cr5Si3, and also silicide of lanthanum and cerium (La,Ce)Si2 were formed. In the course of the work, the Vickers microhardness was measured on the thin sections of the samples under study. The dependence of the values of the microhardness HV on the composition of the experimental samples was established. With increasing silicon concentration for fixed values of chromium, cerium and lanthanum, the microhardness values were increased. Also in the course of this study, the electric conductivity of the experimental samples was determined by a non-contact method in a rotating magnetic field at a temperature of 20 °C. The dependence of the electrical conductivity of the samples on the concentrations of alloying elements was determined. The data obtained in the course of this work may be of interest to engineers in the analysis of the use of rare earth metal additives in bronzes.