Densification Mechanisms in High‐pressure Hot‐Pressing of HfB 2

The fabrication temperature was the principal variable in a kinetic study of the densification of hafnium diboride in high‐pressure hot‐pressing. Densification studies for conventional hot‐pressing were reviewed and correlated with the high‐pressure hot‐pressing results. The consolidation of HfB 2 in the open pore region during high‐pressure hot‐pressing is attributed to particle rearrangement caused by grain boundary sliding and fragmentation. The final stage of densification (relative density >90%) was analyzed in terms of the Nabarro‐Herring vacancy creep model. An activation energy of 22,900 cal/mole was obtained for the rate‐controlling step in the creep process.