O. V. Samoilova, E. A. Trofimov
ABSTRACT
The Cu–Ce–La system is of interest both for the production of bronzes with the addition of rare earth metals, and for the production of amorphous alloys. In the course of this work, we studied the phase composition, structure, and microhardness of 13 cast samples of alloys of the Cu–Ce–La system belonging to the copper angle of the phase diagram of this system. Experimental samples were investigated by the methods of optical microscopy, scanning electron microscopy and X-ray microanalysis analysis, by the method of atomic emission analysis with inductively coupled plasma, by the methods of X-ray phase analysis and thermal analysis. Also on the samples was measured microhardness Vickers HV. The structure of the samples along the grain boundaries of the solid solution based on copper revealed the presence of eutectic, which, according to X-ray microanalysis data, includes copper, lanthanum and cerium. X-ray diffraction data indicate the presence of Cu6Ce and Cu6La compounds in addition to the solid solution based on copper in the samples. The volume fraction of the eutectic component in the sample structure (which is equal to the fraction of the area occupied by the eutectic in the area of thin sections of the samples) was determined. With increasing concentrations of cerium and lanthanum in the composition of the samples, the proportion of the eutectic component also increases. Thermal analysis data indicate the presence of triple eutectic equilibrium in addition to double eutectics. The presence of a strong correlation dependence between the share of the eutectic component in the structure and the microhardness of the experimental samples is shown. With an increase in the share of eutectic in the sample structure, the microhardness index HV also increases. The results obtained may be of interest to practicing materials scientists when analyzing the effect of additives of rare earth metals on the phase composition, structure and mechanical characteristics of copper alloys.
KEYWORDS:
Cu–Ce–La system, phase composition of alloys, structure, microhardness of copper alloys
DOI: 10.1134/S0235010619020038