THE EFFECTS OF NEUTRON IRRADIATION AND PRE-STRAIN ON COMPRESIVE CHARACTERISTIC OF HIGH-PURITY ALUMINUM

Neutron irradiation embrittlement of metal materials is very important in the field of nuclear energy safety, and irradiation hardening could often be used to qualitatively express irradiation embrittlement. Due to a large number of cold-rolled metals have been used in nuclear reactor, and in order to further understand the effects of cold rolling (pre-strain) on the hardening characteristics of neutron irradiation metal materials and its microscopic mechanism, the quasi-static compressive stress-strain relationships of annealed and pre-compressed 10% strain high purity aluminum with different doses were tested, as well as the variation of dislocation density, irradiation void size and number density were also studied in this paper. The results showed that a higher dose induced a bigger size and higher number density of voids, which resulting a stronger hardening effect. The high density dislocations introduced by pre-strain inhibited the nucleation and growth of irradiation voids, and finally reduced the size and number density. With the increase of dose, the softening effect caused by irradiation annealing was stronger than the hardening effect caused by voids, which led to the yield strength of pre-strained high purity aluminum first increasing and then decreasing with dose. Those implies that annealing effect may cause the yield strength of irradiated cold-rolled materials to be lower than that of non-irradiated materials, thus reduce the safety and reliability of cold-rolled metal structures in nuclear reactors. Finally, the B-Y (Byun-Ye) irradiation embrittlement model basing on Johnson-Cook constitutive can be used to predict the compressive constitutive relation of irradiated metal materials, and the prediction effect are in good agreement with the experimental results.