Phase states of the ZrO2-HfO2 system

Despite numerous investigations of the ZrO2-HfO2 system, information on the phase states with the participation of vapor has not been available until now. The problem still remained unclear of the stable existence of the cubic modification for both the pure zirconium and hafnium dioxides, as well as for their solid solutions. The authors constructed on the basis of the experimental data a P-T-x-diagram of the stable phase states of the ZrO2-HfO2 system. The compatibility of a quasibinary approximation was based on the phenomenon of a congruent sublimation and melting of ZrO2 and HfO2. In the present paper a P-T-x-diagram has been constructed of stable and metastable states of the ZrO2-HfO2 system. By means of this diagram it was possible to bring the results of many authors into a single uniform scheme and to explain the behavior of the system both under equilibrium conditions and on deviation from them. 10 refs., 1 fig., 2 tabs