A zirconium-based alloy for the components of the active core of nuclear
reactors comprises (on a weight percent basis): niobium, 0.5-3.0; iron,
0.005-0.5; oxygen, 0.03-0.2; carbon, 0.001-0.04; silicon, 0.002-0.1;
nickel, 0.003-0.02; zirconium being the balance; the alloy structure is
characterized by an .alpha.-solid solution and the .beta. Nb-phase
particles sized below 0.1 .mu.m and having the niobium content of from 60
to 95%. The alloy may further comprise particles of intermetallics
Zr--Fe--Nb with the Fe/Nb ratio of 0.05-0.2. The alloy structure may also
be characterized by an oxygen-hardened .alpha.-solid solution and by the
.beta. Nb-phase particles, and may further comprise particles of
intermetallics Zr--Fe--Nb sized below 0.3 .mu.m.
