The mean-field first-nearest neighbor interaction approximation was used to evaluate the concentration of point defects and site occupancy of micro-alloyed material. The results suggested that micro-alloying had only a slight effect upon point-defect formation. The vacancy concentration decreased, in both Al-rich and Ni-rich alloys, as compared with binary alloys. The concentration of Al antisite defects increased, and that of Ni antisite defects decreased, by about half of the difference in vacancy concentration between the binary and ternary systems on the Al- and Ni-rich sides, respectively. At low concentrations, Ga, Si, Ge, Ti, V, Zr, Nb, Hf and Ta occupied the Al sub-lattice whereas Mn, Fe and Co occupied the Ni sub-lattice. The dependence of occupancy upon composition and temperature was weak. The site preference of Mo, W and Cr changed markedly with alloy chemistry and temperature, and they exhibited a strong tendency to occupy both sub-lattices at high temperature. In general, transition-metal elements in the same period increasingly tended to substitute for Ni with increasing atomic number.

Concentration of Point Defects and Site Occupancy Behavior in Ternary NiAl Alloys. Y.L.Hao, R.Yang, Y.Song, Y.Y.Cui, D.Li, M.Niinomi: Materials Science and Engineering A, 2004, 365[1-2], 85-9