The Isothermal Section Of The Phase Diagram Of The La-Ni-Cu Ternary System At 673K

The isothermal section of the phase diagram of the ternary system La-Ni-Cu has been investigated by X-ray diffraction, differential thermal analysis, optical microscopy and electron microscopy techniques. It consists of 13 single-phase regions, 23 two-phase regions and 11 three-phase regions. At 673 K, the maximum solid solubility of Cu in La2Ni7, LaNi3, La7Ni16, La2Ni3 and LaNi is about 2,2, 3, 3 and 5at.%Cu, respectively. The solid solubility of Cu in La7Ni3 and Ni in LaCu6 is too small to observe. Cu and Ni can replace each other in LaNis and LaCu5, the LaNis and LaCu5 form a continuous solid solution; Cu and Ni form a continuous solid solution too. The maximum solid solubility of Ni in LaCu2 and LaCu is about 15 and 4at%Ni, respectively. A new ternary compound La10Cu85Ni5 has been observed in the La-Ni-Cu ternary system. It belongs to a face-centered cubic lattice. Its lattice constant a is about equal to 1.158nm.