  CuAl2-type transition-metal (Tr) zirconides are superconductor family, and
the Tr-site element substitution largely modifies its transition temperature
(Tc). Here, we synthesized polycrystalline samples of Fe1-xNixZr2 by arc
melting. From magnetic susceptibility measurements, bulk superconductivity was
observed for 0.4 < x < 0.8, and the highest Tc of 2.8 K was observed for x =
0.6. Specific heat measurements were also performed, bulk superconductivity was
observed for 0.4 < x < 0.8, and the highest Tc of 2.6 K was observed for x =
0.6. The obtained superconductivity phase diagram exhibits dome-shaped trend,
which is similar to unconventional superconductors, where magnetic fluctuations
are essential for superconductivity. In addition, from the c/a lattice constant
ratio analysis, we show the possible relationship between the suppression of
bulk superconductivity in the Ni-rich compositions and a collapsed tetragonal
transition.
