Effect of Doped Titanium on Microstructure of UO₂ Microspheres

This paper studies the effect of 0.7% of doped titanium on the microstructure of UO₂ microspheres.The results show that the increasing of the sintering temperature reduces the number of pores,but the volume of each single pore increases instead,which might be due to a fusion between the small pores.In the presence of the doped titanium,the growth rates of grain are inconsistent at a temperature of 1250℃ to 1450℃.Some grains begin to grow rapidly and the distribution of grain sizes shows a "double high" characteristics.However,at the temperature of 1550℃,the grain sizes are distributed in a normal way with the average grain size of about 42 μm.At the temperature of 1250℃ to 1450℃,UO₂ microspheres with doped titanium are sintered with the majority of titanium dioxide uniformly distributed inside the grains in the microspheres and a small amount of titanium dioxide enriching in the grain boundary.While at the sintering temperature of 1550℃,titanium dioxide is most enriched in the grain boundary.