THE ZIRCONIUM-HYDROGEN SYSTEM AT HIGH HYDROGEN CONTENTS

In order to elucidate the phase diagram of the Zr--H system at high hydrogen contents, a pressure-compositiontemperature study of this system in the temperature range 550 to 850 deg C was carried out from ZrH to ZrH/sub 2/. From the obtained isotherms, the position of the boundary between the two-phase ( beta + delta ) region and the single phase delta region was more precisely defined (where beta designates the hydrogen stabilized high temperature zirconium phase, and delta the cubic hydride phase). The isotherm also show no evidence of a two-phase hydride region (cubic + tetragonal hydrides coexisting) in this temperature range, as has been observed at room temperature. (auth