In B-11 NMR experiments, 1/T-1 in the normal state decreases with incr
easing Co concentration. These results suggest the decrease of the den
sity of states for B at E(F) by the Co substitution at the Ni site rat
her than the suppression of AF spin fluctuations of Ni. In Co-59 NMR e
xperiments, T-1(-1) decreases exponentially as exp(-Delta/k(B)T(c)) wi
th further decrease of T with no appreciable enhancement just below T-
c. The ratio 2 Delta/k(B)T(c) was estimated to be about 3 down to 0.5
T-c, which is close to the BCS value of 3.5.