Low-temperature nuclear orientation was applied to study hyperfine interact
ions of Pr-142, Nd-147 and Pm-143,Pm-144 nuclei in Pr0.5Nd0.5Ni single crys
tal. Angular distributions, temperature dependence and external magnetic fi
eld effects on the gamma-ray anisotropy are presented. A Nd-Pm exchange int
eraction seems to dominate the magnetic properties of Pm ions in this syste
m.