Theoretical Study on Effect of Niobium on TiAl(010) Surface Carburization

A hard layer which is rich in niobium and carbon on the surface of TiAl based alloy was formed after plasma Nb alloying followed by plasma carburization. The process parameters of plasma Nb alloying and plasma carburization were modified. This paper investigates diffusion of C atoms on TiAl(010) surface with and without Nb which is transition metal element by using first-principles pseudo potential plane-wave method. By analyzing final energy and forming enthalpy, it is found that the duplex treatment of niobizing and carburization makes the final energy of the surface cell of TiAl(010) enhanced, but it makes forming enthalpy descended, as a result stability of cell improved. After analyzing electron structure it shows that niobizing can weaken the effect of bond of Ti(3d)-Al(3p), which can improve the brittleness. Niobizing also can make the number of electron bonding which locate at thereinafter Fermi level increased, improve the stability of alloy. So this can explain the action of Nb promoting carburization from the view of electron aspectnt.