High Temperature X-Ray Diffraction Investigationof the Zr-H System

Abstract

The phase diagram of the Zr-H system over the range 0 to 65 atomic pct was determined by high temperature X-ray diffraction methods. Results show a eutectoid between α-zirconium and the hydride phase. The eutectoid temperature was established at 560±10°C with a eutectoid composition of 42±3 atomic pct H. The hydride phase of the lowest hydrogen content is stable only above the eutectoid temperature, but is formed and retained in a metastable state during reaction of zirconium with hydrogen at temperatures below 560°C. One hydride phase is indicated that exists over the composition range 55 to 65 atomic pct H.