Vacancy at stacking fault-assisted nucleation of transition-metal carbides and nitrides in Fcc-Fe.

The occupation tendencies of Cr, Cu, Mo, Nb, Ni, Ti and V in Fcc-Fe stacking fault containing vacancy were studied by the first principles calculations. The effects of C, N and Nb, Ti co-segregation in the region of vacancy is discussed. The results are as follows: the substitutional elements Cr, Cu, Mo, Ni, Nb, Ti and interstitial elements C, N have no segregation tendency at the stacking fault of Fcc-Fe (111) plane. When the stacking fault contains vacancy, the above elements have the tendency to segregate around the vacancy, and C, N tend to occupy vacancy and their segregation tendency is the stronger than that of substitutional elements. C, N are easily co-segregated with Nb, Ti in the region of vacancy. It is difficult for Mo to aggregate around the carbonitride precipitates, which is conducive to the use of nano-scale carbide and nitride precipitation strengthening in high Mo austenitic steel, and simultaneously improves corrosion resistance. Nb and Ti tend to aggregate around the vacancy where occupied by C, N. [ABSTRACT FROM AUTHOR]