Fusion neutron irradiation of NiSi alloys at 4. 2K

Two Ni alloys with 4 at.% Si and 12.7 at.% Si in solution have been irradiated at 4.2K with 14 MeV fusion neutrons. The resistivity damage rate of well annealed Ni-4%Si alloy showed an initial transient in the plot of d..delta..rho/d..delta..phit versus ..delta..rho. A high dislocation density appeared to reduce this transient. The resistivity damage rate of Ni-12.7%Si alloy showed an unusual behavior; d..delta..rho/d..delta..phit increases with ..delta..rho after the initial transient period. This behavior is attributed to precipitation and growth of Ni/sub 3/Si during irradiation. Post-irradiation isochronal annealing results showed significant effects of cold work and composition on recovery. Ni-4%Si recovered slower than pure nickel and a high dislocation density enhanced its recovery. For the Ni-12.7% Si alloy, recovery ended after being annealed to 38K, after which the resistivity increased with annealing temperature. This is attributed to further precipitation and growth of Ni/sub 3/Si.