Effect of neutron irradiation on sound attenuation for niobium hydride β-phase

The effect of neutron radiation on sound attenuation in the β-phase of the niobium polycrystalline hybride of NbHsub(0.91) composition is investigated. Measurements of the sound attenuation spectra have been conducted in the 150-400 K temperature range after irradiation with fast neutrons by the fluence Fsub(t)=3x1017 neutr./cm2. Oscillation frequency of the sample made up 1.4 kHz, the maximal deformation amplitude did not exceed approximately 10-6. Irradiation is shown to result in the decrease and expansion of the sound attenuation maximum caused by the motion of double boundaries. Taking into account the fact that introduction of dislocations into the sample results in the same effect it is concluded that the observed radiation effect is caused by the domain boundary interaction with the fields of elastic stresses caused by radiation defects