Vol.21 - 1 Original
Change in Grain Size of Disproportionation Products of Zr2M(M=Co,Ni) with Temperature and Pressure
Masanori HARA, Kuniaki WATANABE
Takashi TSUNEDA*, Tokimasa KAWABATA*, Kenji MATSUDA*,
Susumu IKENO*
Hydrogen Isotope Research Center,
*Mater. Sci. and Eng., Faculty of Eng.,
Toyama University, Gofuku 3190, Toyama 930-8555, Japan
Abstract
Zr2Co disproportionated to ZrH2 and ZrCo
on a wide range of temperatures and pressures. The X-ray diffraction patterns
of disproportionated Zr2Co were constructed broad peaks that
meant to consist of fine crystallite. To evaluate the temperature and pressure
dependence of nucleation of products, the grain size of ZrH2
was calculated on a half width of ZrH2 111 peak by using Sherrer
equation. It was found that the grain size did not depend on disproportionation
conditions such as temperature and pressure. Zr2Ni also disproportionated
and the grain size was not affected by temperature and pressure. These
results indicate that the probability of nucleation does not depend on
temperature and pressure. The disproportionation rates of Zr2M
are determined mainly by the crystal growth rate of products. However,
Zr2NiH5 was formed under the condition of low pressure.
The appearance of disproportionation was affected by amount of absorbed
hydrogen.