The influence of the carbon addition on the microstructure of a U-Nb alloy and the features of Nb2C inclusions

The effects of the carbon addition on the morphology, composition, size distribution and formation mechanism of inclusions in a U-5.5 Nb alloy were discussed. The influence of the carbon content on the microstructure and hardness were also investigated. The methods used in the present study were scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, optical microscopy, and hardness measurements. The results show that the carbon content obviously affects the morphology, size distribution and area fraction of the Nb2C inclusions. Moreover, characterization of the inclusion morphology shows that the Nb2C inclusions form in the liquid and subsequently grow, collide and agglomerate to form clusters. Meanwhile, the average grain size significantly decreases, and the hardness increases with increasing carbon content in the U-5.5 Nb alloy.