Microstructural evolution and densification kinetics during sintering of oxide-dispersed tungsten alloys
Journal
Materials Research Society Symposium Proceedings
Journal Volume
322
Pages
483-489
ISBN
1558992219
Date Issued
1994
Author(s)
Abstract
The present paper discussed the role of ceria and hafnia dispersions in tungsten alloys on the microstructural evolution and densification kinetics during sintering. Densification kinetics were measured using dilatometry, and microstructural changes were examined using scanning electron microscopy and Auger electron spectroscopy. Activation energies for sintering were obtained by analyzed the shift of the iso-density points as a function of linear heating rate. Sintering of both tungsten and ceria-dispersed tungsten were found to be controlled by gain boundary diffusion, with apparent activation energies of 318 ± 21 and 385 ± 15 kJ per mole respectively. However, densification of hafnia-dispersed tungsten is not controlled by a single mechanism. Under different conditions hafnia can enhance or retard densification, the mechanisms associated with this behavior are discussed. In particular, the relationships between sintering behavior and the tungsten-ceria and tungsten-hafnia interfaces are examined. Comparison with conventional oxide dispersoids, such as thoria, will also made.
Other Subjects
Auger electron spectroscopy;Microstructure;Refractory metals;Conventional oxide dispersoids;Multiphase refractory alloys;Oxide-dispersed tungsten alloy;Tungsten alloy microstructural evolution;Tungsten-hafnia interfaces;Tungsten alloys
Type
conference paper