INTERACTION OF TRANSITION AND RARE-EARTH METALS WITH BORON

From our measurements on the R-M-B systems 47 phase equilibria diagrams were constructed and 142 new ternary borides were found. An analysis of the data we obtained showed that the number of ternary compounds in the R-M-B systems increases as the difference between the electronegativities of the transition and rare earth metals increases. The ternary borides of the R-M-B systems are characterized by the formation of new types of structure and by the formation of two homologous series, one based on the CaCu5-type and the CeCo3B2-type structures and the other on the MgZn2-type and the CeCo3B2-type structures. © 1979.