Experimental and thermodynamic assessment of the Gd-Ti-Zr phase diagram

The phase diagram of the ternary Gd-Ti-Zr system has been investigated. The phase equilibria behave as a pseudo-binary Gd-(Ti, Zr) system with the solid state been characterized by the coexistence of elemental Gd and (Ti, Zr) solid solution phase with low solubility (< 1 at%) of the other elements. A continuous eutectic line connects the eutectic points of the binary Gd-Ti and Gd-Zr terminal systems. The stable miscibility gap of the liquid phase of the Gd-Ti system extends up to 15 at%Zr into the ternary alloy system. The liquidus line and phase sequence were experimentally assessed for Gd20Ti40Zr40, Gd40Ti20Zr40 and Gd40Ti50Zr10 by in situ high energy synchrotron X-ray diffraction at elevated temperatures. Based on the experimental data a thermodynamic description of the ternary Gd-Ti-Zr system is derived.