  Using ab initio calculations and special quasirandom structures, we have
characterized the distribution of defect formation energy and migration barrier
in Ni-based solid-solution alloys: Ni_{0.5}Co_{0.5}, Ni_{0.5}Fe_{0.5},
Ni_{0.8}Fe_{0.2} and Ni_{0.8}Cr_{0.2}. As defect formation energies depend
sensitively on elemental chemical potential, we have developed a
computationally efficient method for determining it which takes into account
the global composition and local short-range order. We find that Fe has the
biggest alloy effects for Ni among these four elements. Our results show that
the distribution of migration energies for vacancies and interstitial have a
region of overlap, which will facilitate the recombination between them.
