A study on the phase diagram of Re-Zr refractory system

Abstract

The different volume of Rhenium (Re) and zirconium (Zr) will affect the phase composition and thus change the mechanical properties of the core critical hot end components of gas turbines and aero engines. In this work, the Re-Zr system was studied experimentally by electron probe microanalyses (EPMA) with wavelength dispersive spectrometer (WDS), scanning electron microscopy (SEM) and X-ray diffraction (XRD), and then was measured the phase-transition temperature with the high-speed pyrometer. The phase Re25Zr21 was confirmed to be stable in this system. Besides, the eutectic point of the eutectic reaction Liquid → bcc (Zr) + Re25Zr21 was determined as 14.4% Re by WDS. The present phase transitions (melting point, solidus, and liquidus) measurements indicate that the Re-Zr system is different from the existing Re-Zr phase diagram. Then, the current obtained results, combined with a critical review of the previous publication data, were used to develop the thermodynamic description of the Re-Zr system by utilizing the CALPHAD (CALculation of PHAse Diagram) method. A set of self-consistent thermodynamic parameters was obtained.