A STUDY OF THE ZIRCONIA-HAFNIA SYSTEM.
Summary rept. 1 May 63-30 Apr 64,
IIT RESEARCH INST CHICAGO ILL
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A definitive study of phase relationships in the ZrO2-HfO2 system was conducted. Metallographic, X-ray, differential-thermal, and microprobe analyses were applied to annealed and quenched specimens of arc-melted compositions. The system forms a continuous series of solid solutions in the low-temperature monoclinic structure as well as the high-temperature tetragonal structure. There is a relatively small intervening monoclinic plus tetragonal two-phase solid solution field. This field lies approximately on a straight line connecting the inversion temperatures of the two oxides. The melting points of ZrO2-HfO2 compositions likewise lie roughly on a line connecting the melting point of each oxide. There are no intervening complex oxides. Effort was also directed toward a better definition of the high-temperature, high-hafnium region of the Hf-O system. This study was brought to a conclusion and a final Hf-O diagram is presented. Author
- Ceramics, Refractories and Glass