High temperature phase relations and structure determination of solid solutions in the ternary Nd-Dy-Cu system

The sub-solidus phase relations in the ternary Nd-Dy-Cu system were determined for an isothermal section at 550 °C. The samples were prepared by arc-melting and subsequent annealing in a protective atmosphere for 120 h. The phases in the prepared samples were characterized by X-ray powder diffraction and scanning electron microscopy, and their composition was determined by energy-dispersive spectroscopy. The intermetallic compounds based on the Dy-Cu system are compatible with compounds based on Nd-Cu-based and exhibit a high degree of solid-state solubility. The crystal structures of the solid solutions and their transformations were determined in detail. In the Cu-rich part of the system, the compound DyCu₇, which is stable above 700 °C according to literature data, was confirmed under the applied experimental conditions and is connected to NdCu₆ by a tie line.