Microstructural Characterization of Rhenium Powder Obtained at Various Temperatures

Autor: Rodolfo L. Mannheim, Jorge L. Garin
Rok vydání: 2003
Předmět:
Zdroj: Materials Science Forum. :276-282
ISSN: 1662-9752
DOI: 10.4028/www.scientific.net/msf.416-418.276
Popis: This work deals with the measurement of particle-size distribution of rhenium powder obtained by reduction of ammonium perrhenate under hydrogen flux. Depending upon the reduction temperature, variable amounts of hydrogen, nitrogen and oxygen remain interstitially located in the material, causing large X-ray diffraction line broadening, which accounts for particle-size domains in the microstructure of the metallic particles. The present study was carried out in the range of 400 to 1000 °C, where the oxidized species can be reduced to rhenium powder. All calculations regarding the line-broadening effects made use of the powerfull Warren-Averbach method, while the experimental diffraction profiles were modeled by non-linear least-squares fitting, using pseudo-Voigt functions. The average particle size increased from 8.7 to 120 nm with increasing temperature from 400 to 750 °C, with no further change above this last temperature. On the other side, strain distribution within the same temperature range varied from 15 to 735x10 -5 .
Databáze: OpenAIRE