The ytterbium-copper-aluminium system

The isothermal section of the Yb---Cu---Al phase diagram at 870 K over the whole concentration region has been constructed using X-ray structure and phase analysis. We have confirmed the existence of earlier reported ternary compounds: YbCuAl (ZrNiAl type) and YbCu₄Al₈ (CeMn₄Al₈ type); the previously reported compound YbCu₄Al proved to be a solid solution of aluminium in the binary compound YbCu₅ (CaCu₅). New ternary aluminides such as Yb₄(Cu_0.26Al_0.74)₃₃ (new structure type), Yb₂(Cu_0.57Al_0.43)₁₇ (Th₂Zn₁₇), Yb(Cu_0.85Al_0.15)₆ (YbMo₂Al₄)₇ Yb₆(Cu_0.74Al_0.26)₂₃ (Th₆Mh₂₃) and Yb(Cu_0.30Al_0.70)₃ (PuNi₃) have been prepared for the first time and their crystal structures have been determined. The limits of solid solutions of the binary compound YbCu₅ and the homogeneity ranges of the ternary phases Yb(CuAl)₁₂, Yb(CuAl)₁₇ and Yb(CuAl)₂ have been established.