PHASE RELATIONSHIPS IN ALPHA + DELTA REGION OF ZR-H SYSTEM

The (α + δ)/ δ phase boundary of the Zr-H system has been defined on the basis of studies performed on zirconium hydrides containing 4 at % U. The methods used include optical hot stage microscopy and roomtemperature metallography, dilatometry, and X-ray diffraction. This boundary was found to exist between about 1.33 H/Zr at 550 °C and 1.60 H/Zr at 25 °C. A metastable phase, γ' coexisting with α and δ phases, was found to transform to δ at about 294 °C between 1.20 H/Zr and the (α + δ)/ δ boundary (1.50 H/Zr). © 1969.